Anorexia nervosa

File:Louis Bataille, 'Deux cas d'anorexie hysterique' Wellcome L0020548 (backcropped).jpg

Anorexia nervosa is an eating disorder characterized by attempts to lose weight by way of starvation. A person with anorexia nervosa may exhibit a number of signs and symptoms, the type and severity of which may vary and be present but not readily apparent.{{cite journal |vauthors=Surgenor LJ, Maguire S |title=Assessment of anorexia nervosa: an overview of universal issues and contextual challenges |journal=Journal of Eating Disorders |volume=1 |issue=1 |pages=29 |year=2013 |pmid=24999408 |pmc=4081667 |doi=10.1186/2050-2974-1-29 |doi-access=free}} Though anorexia is typically recognized by the physical manifestations of the illness, it is a mental disorder that can be present at any weight.

Anorexia nervosa, and the associated malnutrition that results from self-imposed starvation, can cause complications in every major organ system in the body.{{cite journal |vauthors=Strumia R |title=Skin signs in anorexia nervosa |journal=Dermato-Endocrinology |volume=1 |issue=5 |pages=268–270 |date=September 2009 |pmid=20808514 |pmc=2836432 |doi=10.4161/derm.1.5.10193}} Malnutrition can cause changes in the brain due to a lack of essential nutrients in the body. Hypokalemia, a drop in the level of potassium in the blood, is a sign of anorexia nervosa.{{cite journal |vauthors=Miller KK |title=Endocrine effects of anorexia nervosa |journal=Endocrinology and Metabolism Clinics of North America |volume=42 |issue=3 |pages= 515–528 |date=September 2013 |pmid=24011884 |pmc=3769686 |doi=10.1016/j.ecl.2013.05.007}} A significant drop in potassium can cause abnormal heart rhythms, constipation, fatigue, muscle damage, and paralysis.{{Cite book |title=Herb, Nutrient, and Drug Interactions: Clinical Implications and Therapeutic Strategies |url=https://books.google.com/books?id=49kLK--eumEC&q=potassium%20decreased%20arrhythmia&pg=PA585 |publisher=Elsevier Health Sciences |date=2008 |access-date=9 April 2015 |isbn=978-0-323-02964-3 |vauthors=Stargrove MB, Treasure J, McKee DL}}

Signs and symptoms may be classified in various categories including: physical, cognitive, affective, behavioral and perceptual:

• A low body mass index for one's age and height (except in cases of atypical anorexia){{cite book |title=Diagnostic and Statistical Manual of Mental Disorders |date=2013-05-22 |publisher=American Psychiatric Association |isbn=978-0-89042-555-8 |page=339 |edition=5th |doi=10.1176/appi.books.9780890425596 |url=https://doi.org/10.1176/appi.books.9780890425596 |access-date=2024-02-29 |last=American Psychiatric Association}}
• Rapid, continuous weight loss{{cite web |title=Anorexia Nervosa |url=http://www.anad.org/get-information/get-informationanorexia-nervosa/ |url-status=live |archive-url=https://web.archive.org/web/20140413130141/http://www.anad.org/get-information/get-informationanorexia-nervosa/ |archive-date=13 April 2014 |access-date=15 April 2014 |publisher=National Association of Anorexia Nervosa and Associated Disorders}}
• Dry hair and skin, hair thinning, as well as hair loss{{Cite journal |last1=Mehler |first1=Philip S. |last2=Brown |first2=Carrie |date=2015-03-31 |title=Anorexia nervosa – medical complications |journal=Journal of Eating Disorders |volume=3 |issue=1 |pages=11 |doi=10.1186/s40337-015-0040-8 |doi-access=free |issn=2050-2974 |pmc=4381361 |pmid=25834735}}
• Low body temperature (hypothermia){{Cite journal |last=Smith |first=Lucille Lakier |date=2021-08-06 |title=The Central Role of Hypothermia and Hyperactivity in Anorexia Nervosa: A Hypothesis |journal=Frontiers in Behavioral Neuroscience |volume=15 |doi=10.3389/fnbeh.2021.700645 |doi-access=free |issn=1662-5153 |pmc=8377352 |pmid=34421554}}
• Raynaud Phenomenon{{Cite journal |last1=Sirufo |first1=Maria Maddalena |last2=Ginaldi |first2=Lia |last3=De Martinis |first3=Massimo |date=2021-05-10 |title=Peripheral Vascular Abnormalities in Anorexia Nervosa: A Psycho-Neuro-Immune-Metabolic Connection |journal=International Journal of Molecular Sciences |language=en |volume=22 |issue=9 |pages=5043 |doi=10.3390/ijms22095043 |doi-access=free |issn=1422-0067 |pmc=8126077 |pmid=34068698}}
• Hypotension or orthostatic hypotension
• Bradycardia or tachycardia
• Chronic fatigue{{Cite book |title=Abnormal Psychology |vauthors=Nolen-Hoeksema S |publisher=McGraw-Hill |year=2013 |isbn=978-0-07-803538-8 |location=New York |pages=339–41}}
• Insomnia
• Having severe muscle tension, aches and pains
• Irregular or absent menstrual{{Cite journal |last1=Poyastro Pinheiro |first1=Andréa |last2=Thornton |first2=Laura M. |last3=Plotonicov |first3=Katherine H. |last4=Tozzi |first4=Federica |last5=Klump |first5=Kelly L. |last6=Berrettini |first6=Wade H. |last7=Brandt |first7=Harry |last8=Crawford |first8=Steven |last9=Crow |first9=Scott |last10=Fichter |first10=Manfred M. |last11=Goldman |first11=David |last12=Halmi |first12=Katherine A. |last13=Johnson |first13=Craig |last14=Kaplan |first14=Allan S. |last15=Keel |first15=Pamela |date=July 2007 |title=Patterns of menstrual disturbance in eating disorders |journal=The International Journal of Eating Disorders |volume=40 |issue=5 |pages=424–434 |doi=10.1002/eat.20388 |issn=0276-3478 |pmid=17497704}} periods
• Infertility
• Gastrointestinal disease{{cite web |vauthors=Hedrick T |title=The Overlap Between Eating Disorders and Gastrointestinal Disorders |website=Nutrition issues in Gastroenterology |publisher=University of Virginia |date=August 2022 |url=https://med.virginia.edu/ginutrition/wp-content/uploads/sites/199/2022/08/August-2022-Eating-Disorders-and-GI-Disorders.pdf |archive-url=https://web.archive.org/web/20240208022520/https://med.virginia.edu/ginutrition/wp-content/uploads/sites/199/2022/08/August-2022-Eating-Disorders-and-GI-Disorders.pdf |archive-date=8 February 2024}}
• Halitosis (from vomiting or starvation-induced ketosis)
• Abdominal distension
• Russell's Sign; can be a tell-tale sign of self-induced vomiting with scratches on the back of the hand
• Tooth erosion
• Lanugo: soft, fine hair growing over the face and body{{cite journal |vauthors=Walsh JM, Wheat ME, Freund K |date=August 2000 |title=Detection, evaluation, and treatment of eating disorders the role of the primary care physician |journal=Journal of General Internal Medicine |volume=15 |issue=8 |pages=577–590 |doi=10.1046/j.1525-1497.2000.02439.x |pmc=1495575 |pmid=10940151}}
• Orange discoloration of the skin, particularly the feet (Carotenosis)

• An obsession with counting calories and monitoring contents of food
• Preoccupation with food, recipes, or cooking; may cook elaborate dinners for others, but not eat the food themselves or consume a very small portion
• Admiration of thinner people
• Thoughts of being fat or not thin enough{{Cite journal |last=Walsh |first=B. Timothy |date=May 2013 |title=The Enigmatic Persistence of Anorexia Nervosa |journal=American Journal of Psychiatry |volume=170 |issue=5 |pages=477–484 |doi=10.1176/appi.ajp.2012.12081074 |issn=0002-953X |pmc=4095887 |pmid=23429750}}
• An altered mental representation of one's body
• Impaired theory of mind, exacerbated by lower BMI and depression{{cite journal |vauthors=Bora E, Köse S |title=Meta-analysis of theory of mind in anorexia nervosa and bulimia nervosa: A specific İmpairment of cognitive perspective taking in anorexia nervosa? |journal=The International Journal of Eating Disorders |volume=49 |issue=8 |pages=739–740 |date=August 2016 |pmid=27425037 |doi=10.1002/eat.22572 |hdl=11343/291969 |hdl-access=free}}
• Memory impairment
• Difficulty in abstract thinking and problem solving
• Rigid and inflexible thinking
• Poor self-esteem
• Hypercriticism and perfectionism

• Depression
• Ashamed of oneself or one's body
• Anxiety disorders
• Rapid mood swings
• Emotional dysregulation
• Alexithymia

• Compulsive weighing
• Regular body checking
• Food restriction, both in terms of caloric content and type (for example, macronutrient groups)
• Food rituals, such as cutting food into tiny pieces and measuring it, refusing to eat around others, and hiding or discarding of food
• Purging, which may be achieved through self-induced vomiting, laxatives, diet pills, emetics, diuretics, or exercise. The goals of purging are various, including the prevention of weight gain, discomfort with the physical sensation of being full or bloated, and feelings of guilt or impurity.{{Cite web |date=2017-08-23 |title=Anorexia nervosa |url=https://nedc.com.au/eating-disorders/eating-disorders-explained/types/anorexia-nervosa/ |access-date=2022-09-19 |work=National Eating Disorders Collaboration (NEDC) |language=en-AU}}
• Excessive exercise{{cite journal |vauthors=Marzola E, Nasser JA, Hashim SA, Shih PA, Kaye WH |date=November 2013 |title=Nutritional rehabilitation in anorexia nervosa: review of the literature and implications for treatment |journal=BMC Psychiatry |volume=13 |issue=1 |pages=290 |doi=10.1186/1471-244X-13-290 |pmc=3829207 |pmid=24200367 |doi-access=free}} or compulsive movement,{{cite book |title=Community treatment of eating disorders |vauthors=Robinson PH |date=2006 |publisher=John Wiley & Sons |isbn=978-0-470-01676-3 |location=Chichester |page=66}} such as pacing
• Self harming or self-loathing
• Social withdrawal and solitude, stemming from the avoidance of friends, family, and events where food may be present
• Excessive water consumption to create a false impression of satiety
• Excessive caffeine consumption

• Unawareness or denial of severity of condition (anosognosia),{{Cite book |last=Gaudiani |first=Jennifer |title=Sick Enough: A Guide to the Medical Complications of Eating Disorders |date=October 2, 2018 |publisher=Routledge |isbn=978-0815382454 |edition=1st}} which may prevent some from seeking recovery
• Perception of self as heavier or fatter than in reality, i.e., body image disturbance
• Altered body schema, i.e., a distorted and unconscious perception of one's body size and shape that influences how the individual experiences their body during physical activities. For example, a patient with anorexia nervosa may genuinely fear that they cannot fit through a narrow passageway. However, due to their malnourished state, their body is significantly smaller than someone with a normal BMI who would actually struggle to fit through the same space. In spite of having a small frame, the patient's altered body schema leads them to perceive their body as larger than it is.{{Citation needed|date=February 2025}}

Interoception involves the conscious and unconscious sense of the internal state of the body, and it has an important role in homeostasis and regulation of emotions.{{cite journal |vauthors=Khalsa SS, Adolphs R, Cameron OG, Critchley HD, Davenport PW, Feinstein JS, Feusner JD, Garfinkel SN, Lane RD, Mehling WE, Meuret AE, Nemeroff CB, Oppenheimer S, Petzschner FH, Pollatos O, Rhudy JL, Schramm LP, Simmons WK, Stein MB, Stephan KE, Van den Bergh O, Van Diest I, von Leupoldt A, Paulus MP |title=Interoception and Mental Health: A Roadmap |journal=Biological Psychiatry. Cognitive Neuroscience and Neuroimaging |volume=3 |issue=6 |pages=501–513 |date=June 2018 |pmid=29884281 |pmc=6054486 |doi=10.1016/j.bpsc.2017.12.004}} Aside from noticeable physiological dysfunction, interoceptive deficits also prompt individuals with anorexia to concentrate on distorted perceptions of multiple elements of their body image.{{cite journal |vauthors=Badoud D, Tsakiris M |title=From the body's viscera to the body's image: Is there a link between interoception and body image concerns? |journal=Neuroscience and Biobehavioral Reviews |volume=77 |pages=237–246 |date=June 2017 |pmid=28377099 |doi=10.1016/j.neubiorev.2017.03.017 |s2cid=768206}} This exists in both people with anorexia and in healthy individuals due to impairment in interoceptive sensitivity and interoceptive awareness.

Aside from weight gain and outer appearance, people with anorexia also report abnormal bodily functions such as indistinct feelings of fullness.{{cite journal |vauthors=Khalsa SS, Lapidus RC |title=Can Interoception Improve the Pragmatic Search for Biomarkers in Psychiatry? |journal=Frontiers in Psychiatry |volume=7 |pages=121 |date=2016 |pmid=27504098 |pmc=4958623 |doi=10.3389/fpsyt.2016.00121 |doi-access=free}} This provides an example of miscommunication between internal signals of the body and the brain. Due to impaired interoceptive sensitivity, powerful cues of fullness may be detected prematurely in highly sensitive individuals, which can result in decreased calorie consumption and generate anxiety surrounding food intake in anorexia patients.{{Cite journal |vauthors=Boswell JF, Anderson LM, Anderson DA |date= June 2015|title=Integration of Interoceptive Exposure in Eating Disorder Treatment |journal=Clinical Psychology: Science and Practice |language=en |volume=22 |issue=2 |pages=194–210 |doi=10.1111/cpsp.12103}} People with anorexia also report difficulty identifying and describing their emotional feelings and the inability to distinguish emotions from bodily sensations in general, called alexithymia.

Interoceptive awareness and emotion are deeply intertwined, and could mutually impact each other in abnormalities. Anorexia patients also exhibit emotional regulation difficulties that ignite emotionally-cued eating behaviors, such as restricting food or excessive exercising. Impaired interoceptive sensitivity and interoceptive awareness can lead anorexia patients to adapt distorted interpretations of weight gain that are cued by physical sensations related to digestion (e.g., fullness). Combined, these interoceptive and emotional elements could together trigger maladaptive and negatively reinforced behavioral responses that assist in the maintenance of anorexia. In addition to metacognition, people with anorexia also have difficulty with social cognition including interpreting others' emotions, and demonstrating empathy.{{cite journal |vauthors=Kasperek-Zimowska BJ, Zimowski JG, Biernacka K, Kucharska-Pietura K, Rybakowski F |title=Impaired social cognition processes in Asperger syndrome and anorexia nervosa. In search for endophenotypes of social cognition |journal=Psychiatria Polska |volume=50 |issue=3 |pages=533–542 |year=2014 |pmid=27556112 |doi=10.12740/PP/OnlineFirst/33485 |doi-access=free}} Abnormal interoceptive awareness and interoceptive sensitivity shown through all of these examples have been observed so frequently in anorexia that they have become key characteristics of the illness.

Other psychological issues may factor into anorexia nervosa. Some pre-existing disorders can increase a person's likelihood to develop an eating disorder. Additionally, anorexia nervosa can contribute to the development of certain conditions.{{cite journal |vauthors=Strober M, Freeman R, Lampert C, Diamond J |title=The association of anxiety disorders and obsessive compulsive personality disorder with anorexia nervosa: evidence from a family study with discussion of nosological and neurodevelopmental implications |journal=The International Journal of Eating Disorders |volume=40 |issue=S3 |pages=S46–S51 |date=November 2007 |pmid=17610248 |doi=10.1002/eat.20429 |doi-access=free}} The presence of psychiatric comorbidity has been shown to affect the severity and type of anorexia nervosa symptoms in both adolescents and adults.{{cite journal |vauthors=Brand-Gothelf A, Leor S, Apter A, Fennig S |title=The impact of comorbid depressive and anxiety disorders on severity of anorexia nervosa in adolescent girls |language=en-US |journal=The Journal of Nervous and Mental Disease |volume=202 |issue=10 |pages=759–762 |date=October 2014 |pmid=25265267 |doi=10.1097/NMD.0000000000000194 |s2cid=6023688}}

Post traumatic stress disorder remains highly prevalent among patients with anorexia nervosa, with more comorbid PTSD being associated with more severe eating disorder symptoms.{{Cite journal |last=Rijkers |first=Cleo |title=Eating disorders and posttraumatic stress disorder |journal=Current Opinion in Psychiatry |date=2019 |volume=32 |issue=6 |pages=510–517|doi=10.1097/YCO.0000000000000545 |pmid=31313708 |url=https://pure.rug.nl/ws/files/118591933/Eating_disorders_and_posttraumatic_stress_disorder.8.pdf}} Obsessive-compulsive disorder (OCD) and obsessive-compulsive personality disorder (OCPD) are highly comorbid with AN.{{cite journal |vauthors=Godier LR, Park RJ |title=Compulsivity in anorexia nervosa: a transdiagnostic concept |journal=Frontiers in Psychology |volume=5 |pages=778 |year=2014 |pmid=25101036 |pmc=4101893 |doi=10.3389/fpsyg.2014.00778 |doi-access=free}}{{cite journal |vauthors=Halmi KA, Tozzi F, Thornton LM, Crow S, Fichter MM, Kaplan AS, Keel P, Klump KL, Lilenfeld LR, Mitchell JE, Plotnicov KH, Pollice C, Rotondo A, Strober M, Woodside DB, Berrettini WH, Kaye WH, Bulik CM |title=The relation among perfectionism, obsessive-compulsive personality disorder and obsessive-compulsive disorder in individuals with eating disorders |journal=The International Journal of Eating Disorders |volume=38 |issue=4 |pages=371–374 |date=December 2005 |pmid=16231356 |doi=10.1002/eat.20190 |doi-access=free}} OCD is linked with more severe symptomatology and worse prognosis.{{cite journal |vauthors=Crane AM, Roberts ME, Treasure J |title=Are obsessive-compulsive personality traits associated with a poor outcome in anorexia nervosa? A systematic review of randomized controlled trials and naturalistic outcome studies |journal=The International Journal of Eating Disorders |volume=40 |issue=7 |pages=581–588 |date=November 2007 |pmid=17607713 |doi=10.1002/eat.20419 |doi-access=free}} The causality between personality disorders and eating disorders has yet to be fully established.{{cite journal |vauthors=Gárriz M, Andrés-Perpiñá S, Plana MT, Flamarique I, Romero S, Julià L, Castro-Fornieles J |title=Personality disorder traits, obsessive ideation and perfectionism 20 years after adolescent-onset anorexia nervosa: a recovered study |journal=Eating and Weight Disorders |volume=26 |issue=2 |pages=667–677 |date=March 2021 |pmid=32350776 |doi=10.1007/s40519-020-00906-7 |quote=However, prospective studies are still scarce and the results from current literature regarding causal connections between AN and personality are unavailable. |s2cid=216649851}} Other comorbid conditions include depression,{{cite journal |vauthors=Casper RC |title=Depression and eating disorders |journal=Depression and Anxiety |volume=8 |issue=Suppl 1 |pages=96–104 |year=1998 |pmid=9809221 |doi=10.1002/(SICI)1520-6394(1998)8:1+<96::AID-DA15>3.0.CO;2-4 |s2cid=36772859 |doi-access=free}} alcoholism,{{Cite book |title=Handbook of Alcoholism |page=[https://books.google.com/books?id=NE5iD_nNygcC&pg=PA293 293] |publisher=CRC Press |date=24 March 2000 |isbn=978-1-4200-3696-1 |vauthors=Zernig G, Saria A, Kurz M, O'Malley S}} substance abuse,{{Cite journal |last1=Devoe |first1=Daniel J. |last2=Dimitropoulos |first2=Gina |last3=Anderson |first3=Alida |last4=Bahji |first4=Anees |last5=Flanagan |first5=Jordyn |last6=Soumbasis |first6=Andrea |last7=Patten |first7=Scott B. |last8=Lange |first8=Tom |last9=Paslakis |first9=Georgios |date=2021-12-11 |title=The prevalence of substance use disorders and substance use in anorexia nervosa: a systematic review and meta-analysis |journal=Journal of Eating Disorders |volume=9 |issue=1 |pages=161 |doi=10.1186/s40337-021-00516-3 |doi-access=free |issn=2050-2974 |pmc=8666057 |pmid=34895358}} borderline and other personality disorders,{{Cite book |title=Personality Disorders and Eating Disorders: Exploring the Frontier |page=[https://books.google.com/books?id=gpEkZIQSML4C&pg=PA28 28] |publisher=Routledge |date=21 August 2013 |isbn=978-1-135-44280-4 |vauthors=Sansone RA, Levitt JL}}{{cite journal |vauthors=Halmi KA |title=Perplexities of treatment resistance in eating disorders |journal=BMC Psychiatry |volume=13 |pages=292 |date=November 2013 |pmid=24199597 |pmc=3829659 |doi=10.1186/1471-244X-13-292 |doi-access=free}} anxiety disorders,{{cite journal |vauthors=Swinbourne JM, Touyz SW |title=The co-morbidity of eating disorders and anxiety disorders: a review |journal=European Eating Disorders Review |volume=15 |issue=4 |pages=253–274 |date=July 2007 |pmid=17676696 |doi=10.1002/erv.784 |doi-access=free}} attention deficit hyperactivity disorder,{{cite journal |vauthors=Cortese S, Bernardina BD, Mouren MC |title=Attention-deficit/hyperactivity disorder (ADHD) and binge eating |journal=Nutrition Reviews |volume=65 |issue=9 |pages=404–411 |date=September 2007 |pmid=17958207 |doi=10.1111/j.1753-4887.2007.tb00318.x |doi-access=free}} and body dysmorphic disorder (BDD).{{Cite book |title=Cognitive-Behavioral Therapy for Body Dysmorphic Disorder: A Treatment Manual |page=[https://books.google.com/books?id=SmbNhYMod8gC&pg=PA270 270] |publisher=Guilford Press |date=18 December 2012 |isbn=978-1-4625-0790-0 |vauthors=Wilhelm S, Phillips KA, Steketee G}} Depression and anxiety are the most common comorbidities,{{cite journal |vauthors=Berkman ND, Bulik CM, Brownley KA, Lohr KN, Sedway JA, Rooks A, Gartlehner G |title=Management of eating disorders |journal=Evidence Report/Technology Assessment |issue=135 |pages=1–166 |date=April 2006 |pmid=17628126 |pmc=4780981 |url=http://archive.ahrq.gov/downloads/pub/evidence/pdf/eatingdisorders/eatdis.pdf |url-status=live |df=dmy-all |archive-url=https://web.archive.org/web/20141222114708/http://archive.ahrq.gov/downloads/pub/evidence/pdf/eatingdisorders/eatdis.pdf |archive-date=22 December 2014}} and depression is associated with a worse outcome.

Autism spectrum disorders occur more commonly among people with eating disorders than in the general population,{{cite journal |vauthors=Huke V, Turk J, Saeidi S, Kent A, Morgan JF |title=Autism spectrum disorders in eating disorder populations: a systematic review |journal=European Eating Disorders Review |volume=21 |issue=5 |pages=345–351 |date=September 2013 |pmid=23900859 |doi=10.1002/erv.2244}} with about 30% of children and adults with AN likely having autism.{{Cite journal |last1=Inal-Kaleli |first1=Ipek |last2=Dogan |first2=Nurhak |last3=Kose |first3=Sezen |last4=Bora |first4=Emre |date=2024-11-12 |title=Investigating the Presence of Autistic Traits and Prevalence of Autism Spectrum Disorder Symptoms in Anorexia Nervosa: A Systematic Review and Meta-Analysis |journal=The International Journal of Eating Disorders |volume=58 |issue=1 |pages=66–90 |doi=10.1002/eat.24307 |issn=1098-108X |pmid=39530423 |doi-access=free |pmc=11784827}} Zucker et al. (2007) proposed that conditions on the autism spectrum make up the cognitive endophenotype underlying anorexia nervosa and appealed for increased interdisciplinary collaboration.{{cite journal |vauthors=Zucker NL, Losh M, Bulik CM, LaBar KS, Piven J, Pelphrey KA |title=Anorexia nervosa and autism spectrum disorders: guided investigation of social cognitive endophenotypes |journal=Psychological Bulletin |volume=133 |issue=6 |pages=976–1006 |date=November 2007 |pmid=17967091 |doi=10.1037/0033-2909.133.6.976 |url=http://www.duke.edu/web/mind/level2/faculty/labar/pdfs/Zucker_et_al_2007.pdf |url-status=live |df=dmy-all |archive-url=https://web.archive.org/web/20100420183125/http://www.duke.edu/web/mind/level2/faculty/labar/pdfs/Zucker_et_al_2007.pdf |archive-date=20 April 2010}}

There is evidence for biological, psychological, developmental, and sociocultural risk factors, but the exact cause of eating disorders is unknown.{{cite journal |vauthors=Rikani AA, Choudhry Z, Choudhry AM, Ikram H, Asghar MW, Kajal D, Waheed A, Mobassarah NJ |date=October 2013 |title=A critique of the literature on etiology of eating disorders |journal=Annals of Neurosciences |volume=20 |issue=4 |pages=157–161 |doi=10.5214/ans.0972.7531.200409 |pmc=4117136 |pmid=25206042}}

File:Association of Anorexia nervosa with psychiatric and metabolic traits.jpg

Anorexia nervosa is highly heritable. Twin studies have shown a heritability rate of 28–58%.{{cite book |vauthors=Thornton LM, Mazzeo SE, Bulik CM |chapter=The heritability of eating disorders: methods and current findings |title=Behavioral Neurobiology of Eating Disorders |volume=6 |pages=141–56 |year=2011 |pmid=21243474 |pmc=3599773 |doi=10.1007/7854_2010_91 |series=Current Topics in Behavioral Neurosciences |isbn=978-3-642-15130-9}} First-degree relatives of those with anorexia have roughly 12 times the risk of developing anorexia.{{cite book |vauthors=Hildebrandt T, Downey A |veditors=Charney D, Sklar P, Buxbaum J, Nestler E |title=Neurobiology of Mental Illness |publisher=Oxford University Press |isbn=978-0-19-993495-9 |edition=4th |chapter=The Neurobiology of Eating Disorders |date=4 July 2013}} Association studies have been performed, studying 128 different polymorphisms related to 43 genes including genes involved in regulation of eating behavior, motivation and reward mechanics, personality traits and emotion. Consistent associations have been identified for polymorphisms associated with agouti-related peptide, brain derived neurotrophic factor, catechol-o-methyl transferase, SK3 and opioid receptor delta-1.{{cite journal |vauthors=Rask-Andersen M, Olszewski PK, Levine AS, Schiöth HB |title=Molecular mechanisms underlying anorexia nervosa: focus on human gene association studies and systems controlling food intake |journal=Brain Research Reviews |volume=62 |issue=2 |pages=147–164 |date=March 2010 |pmid=19931559 |doi=10.1016/j.brainresrev.2009.10.007 |s2cid=37635456}} Epigenetic modifications, such as DNA methylation, may contribute to the development or maintenance of anorexia nervosa, though clinical research in this area is in its infancy.{{cite journal |vauthors=Pjetri E, Schmidt U, Kas MJ, Campbell IC |title=Epigenetics and eating disorders |journal=Current Opinion in Clinical Nutrition and Metabolic Care |volume=15 |issue=4 |pages=330–335 |date=July 2012 |pmid=22617563 |doi=10.1097/MCO.0b013e3283546fd3 |s2cid=27183934}}{{cite journal |vauthors=Hübel C, Marzi SJ, Breen G, Bulik CM |title=Epigenetics in eating disorders: a systematic review |journal=Molecular Psychiatry |volume=24 |issue=6 |pages=901–915 |date=June 2019 |pmid=30353170 |pmc=6544542 |doi=10.1038/s41380-018-0254-7}}

A 2019 study found a genetic relationship with mental disorders, such as schizophrenia, obsessive–compulsive disorder, anxiety disorder and depression; and metabolic functioning with a negative correlation with fat mass, type 2 diabetes and leptin.{{cite journal |vauthors=Watson HJ, Yilmaz Z, Thornton LM, Hübel C, Coleman JR, Gaspar HA, etal |title=Genome-wide association study identifies eight risk loci and implicates metabo-psychiatric origins for anorexia nervosa |journal=Nature Genetics |volume=51 |issue=8 |pages=1207–1214 |date=August 2019 |pmid=31308545 |pmc=6779477 |doi=10.1038/s41588-019-0439-2}}

Obstetric complications: prenatal and perinatal complications may factor into the development of anorexia nervosa, such as preterm birth,{{cite journal |vauthors=Larsen JT, Bulik CM, Thornton LM, Koch SV, Petersen L |title=Prenatal and perinatal factors and risk of eating disorders |journal=Psychological Medicine |volume=51 |issue=5 |pages=870–880 |date=April 2021 |pmid=31910913 |doi=10.1017/S0033291719003945 |s2cid=210086516 |url=https://cdr.lib.unc.edu/downloads/8g84mw99r}} maternal anemia, diabetes mellitus, preeclampsia, placental infarction, and neonatal heart abnormalities.{{cite journal |vauthors=Jones C, Pearce B, Barrera I, Mummert A |title=Fetal programming and eating disorder risk |journal=Journal of Theoretical Biology |volume=428 |pages=26–33 |date=September 2017 |pmid=28571669 |doi=10.1016/j.jtbi.2017.05.028 |bibcode=2017JThBi.428...26J}} Neonatal complications may also have an influence on harm avoidance, one of the personality traits associated with the development of AN.{{cite journal |vauthors=Favaro A, Tenconi E, Santonastaso P |title=Perinatal factors and the risk of developing anorexia nervosa and bulimia nervosa |journal=Archives of General Psychiatry |volume=63 |issue=1 |pages=82–88 |date=January 2006 |pmid=16389201 |doi=10.1001/archpsyc.63.1.82 |s2cid=45181444}}

Neuroendocrine dysregulation: altered signaling of peptides that facilitate communication between the gut, brain and adipose tissue, such as ghrelin, leptin, neuropeptide Y and orexin, may contribute to the pathogenesis of anorexia nervosa by disrupting regulation of hunger and satiety.{{cite book |chapter=24. Orexigenic Hypothalamic Peptides Behavior and Feeding – 24.5 Orexin |pages=[https://books.google.com/books?id=KuAEPOPbW6MC&pg=PA361 361–2] |vauthors=Davis JF, Choi DL, Benoit SC |title=Handbook of Behavior, Food and Nutrition |veditors=Preedy VR, Watson RR, Martin CR |publisher=Springer |year=2011 |isbn=978-0-387-92271-3}}{{cite journal |vauthors=Smitka K, Papezova H, Vondra K, Hill M, Hainer V, Nedvidkova J |title=The role of "mixed" orexigenic and anorexigenic signals and autoantibodies reacting with appetite-regulating neuropeptides and peptides of the adipose tissue-gut-brain axis: relevance to food intake and nutritional status in patients with anorexia nervosa and bulimia nervosa |journal=International Journal of Endocrinology |volume=2013 |pages=483145 |year=2013 |pmid=24106499 |pmc=3782835 |doi=10.1155/2013/483145 |doi-access=free}}

Gastrointestinal diseases: people with gastrointestinal disorders may be more at risk of developing disorders of eating practices than the general population, principally restrictive eating disturbances.{{cite journal |vauthors=Satherley R, Howard R, Higgs S |title=Disordered eating practices in gastrointestinal disorders |journal=Appetite |volume=84 |pages=240–250 |date=January 2015 |pmid=25312748 |doi=10.1016/j.appet.2014.10.006 |url=http://pure-oai.bham.ac.uk/ws/files/18572989/Satherley_Disordered_eating_practices_gastrointestinal_disorders_Appetite_2014.pdf |access-date=4 July 2019 |url-status=dead |s2cid=25805182 |archive-url=https://web.archive.org/web/20190924082720/http://pure-oai.bham.ac.uk/ws/files/18572989/Satherley_Disordered_eating_practices_gastrointestinal_disorders_Appetite_2014.pdf |archive-date=24 September 2019 |type=Review}} An association of anorexia nervosa with celiac disease has been found.{{cite journal |vauthors=Bern EM, O'Brien RF |title=Is it an eating disorder, gastrointestinal disorder, or both? |journal=Current Opinion in Pediatrics |volume=25 |issue=4 |pages=463–470 |date=August 2013 |pmid=23838835 |doi=10.1097/MOP.0b013e328362d1ad |type=Review |s2cid=5417088 |quote=Several case reports brought attention to the association of anorexia nervosa and celiac disease.(...) Some patients present with the eating disorder prior to diagnosis of celiac disease and others developed anorexia nervosa after the diagnosis of celiac disease. Healthcare professionals should screen for celiac disease with eating disorder symptoms especially with gastrointestinal symptoms, weight loss, or growth failure.(...) Celiac disease patients may present with gastrointestinal symptoms such as diarrhea, steatorrhea, weight loss, vomiting, abdominal pain, anorexia, constipation, bloating, and distension due to malabsorption. Extraintestinal presentations include anemia, osteoporosis, dermatitis herpetiformis, short stature, delayed puberty, fatigue, aphthous stomatitis, elevated transaminases, neurologic problems, or dental enamel hypoplasia.(...) it has become clear that symptomatic and diagnosed celiac disease is the tip of the iceberg; the remaining 90% or more of children are asymptomatic and undiagnosed.}} Individuals with good dietary management may develop anxiety, food aversion and eating disorders because of concerns around cross contamination of their foods. Some authors suggest that medical professionals should evaluate the presence of unrecognized celiac disease in all people with an eating disorder, especially if they present any gastrointestinal symptoms, (such as decreased appetite, abdominal pain, bloating, distension, vomiting, diarrhea or constipation), weight loss, or growth failure. With routinely asking celiac patients about weight or body shape concerns, dieting or vomiting for weight control, to evaluate the possible presence of an eating disorders, especially in women.{{cite journal |vauthors=Quick VM, Byrd-Bredbenner C, Neumark-Sztainer D |title=Chronic illness and disordered eating: a discussion of the literature |journal=Advances in Nutrition |volume=4 |issue=3 |pages=277–286 |date=May 2013 |pmid=23674793 |pmc=3650496 |doi=10.3945/an.112.003608 |type=Review}}

Anorexia nervosa is more likely to occur in a person's pubertal years. Some explanatory hypotheses for the rising prevalence of eating disorders in adolescence are "increase of adipose tissue in girls, hormonal changes of puberty, societal expectations of increased independence and autonomy that are particularly difficult for anorexic adolescents to meet; [and] increased influence of the peer group and its values."

Studies have hypothesized that disordered eating patterns may also arise secondary to starvation.{{Cite journal |last1=van Eeden |first1=Annelies E. |last2=van Hoeken |first2=Daphne |last3=Hoek |first3=Hans W. |date=2021-09-16 |title=Incidence, prevalence and mortality of anorexia nervosa and bulimia nervosa |journal=Current Opinion in Psychiatry |language=en |volume=34 |issue=6 |pages=515–524 |doi=10.1097/YCO.0000000000000739 |pmid=34419970 |pmc=8500372 |issn=0951-7367}}{{Cite journal |last1=Christensen |first1=Kara A. |last2=Forbush |first2=Kelsie T. |last3=Richson |first3=Brianne N. |last4=Thomeczek |first4=Marianna L. |last5=Perko |first5=Victoria L. |last6=Bjorlie |first6=Kayla |last7=Christian |first7=Kylie |last8=Ayres |first8=Joseph |last9=Wildes |first9=Jennifer E. |last10=Mildrum Chana |first10=Sofia |date=2021-04-22 |title=Food insecurity associated with elevated eating disorder symptoms, impairment, and eating disorder diagnoses in an American University student sample before and during the beginning of the COVID-19 pandemic |journal=International Journal of Eating Disorders |language=en |volume=54 |issue=7 |pages=1213–1223 |doi=10.1002/eat.23517 |pmid=33885180 |pmc=8250281 |issn=0276-3478}} The results of the Minnesota Starvation Experiment, for example, showed that normal controls will exhibit many of the same behavioral patterns associated with AN when subjected to starvation. Similarly, scientific experiments conducted using mice have suggested that other mammals exhibit these same behaviors, especially compulsive movement, when caloric restriction is induced,{{Cite journal |last1=Chen |first1=Danica |last2=Steele |first2=Andrew D. |last3=Lindquist |first3=Susan |last4=Guarente |first4=Leonard |date=2005-12-09 |title=Increase in activity during calorie restriction requires Sirt1 |journal=Science |volume=310 |issue=5754 |pages=1641 |doi=10.1126/science.1118357 |issn=1095-9203 |pmid=16339438}} likely mediated by various changes in the neuroendocrine system.{{cite journal |vauthors=Zandian M, Ioakimidis I, Bergh C, Södersten P |title=Cause and treatment of anorexia nervosa |journal=Physiology & Behavior |volume=92 |issue=1–2 |pages=283–290 |date=September 2007 |pmid=17585973 |doi=10.1016/j.physbeh.2007.05.052 |s2cid=43620773}}{{Cite book |vauthors=Thambirajah MS |title=Case Studies in Child and Adolescent Mental Health |publisher=Radcliffe Publishing |year=2007 |page=145 |isbn=978-1-85775-698-2 |oclc=84150452}}{{cite journal |vauthors=Kaye W |title=Neurobiology of anorexia and bulimia nervosa |journal=Physiology & Behavior |volume=94 |issue=1 |pages=121–135 |date=April 2008 |pmid=18164737 |pmc=2601682 |doi=10.1016/j.physbeh.2007.11.037}} This has given further rise to the hypothesis that anorexia nervosa and other restrictive eating disorders may be an evolutionarily advantageous adaptive response to a perceived famine in the environment.{{Cite journal |last=Guisinger |first=Shan |date=October 2003 |title=Adapted to flee famine: adding an evolutionary perspective on anorexia nervosa |journal=Psychological Review |volume=110 |issue=4 |pages=745–761 |doi=10.1037/0033-295X.110.4.745 |issn=0033-295X |pmid=14599241}}{{cite web |last1=Guisinger |first1=Shan |title=Adapted to Famine: An Evolutionary Approach to Understanding Eating Behaviors |url=https://www.adaptedtofamine.com/ |archive-url=https://web.archive.org/web/20240622192109/https://www.adaptedtofamine.com/ |archive-date=2024-06-22}} Recent research has further expanded this perspective, showing how caloric restriction may be adaptive in volatile or uncertain environment - thus potentially explaining the association between an increased risk to develop anorexia nervosa and adverse childhood experiences.{{Cite journal |last1=Rossi |first1=Eleonora |last2=Cassioli |first2=Emanuele |last3=Dani |first3=Cristiano |last4=Marchesoni |first4=Giorgia |last5=Monteleone |first5=Alessio M. |last6=Wonderlich |first6=Stephen A. |last7=Ricca |first7=Valdo |last8=Castellini |first8=Giovanni |date=2024-05-01 |title=The maltreated eco-phenotype of eating disorders: A new diagnostic specifier? A systematic review of the evidence and comprehensive description |url=https://linkinghub.elsevier.com/retrieve/pii/S0149763424000885 |journal=Neuroscience & Biobehavioral Reviews |volume=160 |pages=105619 |doi=10.1016/j.neubiorev.2024.105619 |pmid=38462152 |issn=0149-7634|hdl=2158/1352632 |hdl-access=free}}

Early theories of the cause of anorexia linked it to childhood sexual abuse or dysfunctional families;{{cite journal |vauthors=Connors ME, Morse W |title=Sexual abuse and eating disorders: a review |journal=The International Journal of Eating Disorders |volume=13 |issue=1 |pages=1–11 |date=January 1993 |pmid=8477269 |doi=10.1002/1098-108x(199301)13:1<1::aid-eat2260130102>3.0.co;2-p}} evidence is conflicting, and well-designed research is needed. The fear of food is known as sitiophobia{{cite book |vauthors=Worthen D |title=P & G Pharmacy Handbook |location=Boca Raton, FL |publisher=Routledge |date=2001 |page=65 |isbn=978-1-4822-9648-8}} or cibophobia,{{cite book |vauthors=Ensminger AH |title=Foods and Nutrition Encyclopedia |edition = 1st |publisher=Pegus Press |location=Clovis, California |date=1983 |page=423 |isbn=978-0-941218-05-4}} and is part of the differential diagnosis.{{cite book |vauthors=Colman A |title=A Dictionary of Psychology |date=2015 |publisher=Oxford University Press |isbn=978-0-19-105784-7 |page=851 |url=https://books.google.com/books?id=zvlrBgAAQBAJ&pg=PA851}}{{cite book |vauthors=Rogers AI, Vanderveldt HS, Deshpande AR |chapter=Weight Loss |veditors=Hawkey CJ, Bosch J, Richter JE, Garcia-Tsao G, Chan FK |title=Textbook of Clinical Gastroenterology and Hepatology |date=2012 |publisher=John Wiley & Sons |isbn=978-1-118-32142-3 |page=69 |edition=2nd |chapter-url=https://books.google.com/books?id=5Mrl2t6P9QwC&pg=PA69}} Other psychological causes of anorexia include low self-esteem, feeling as if there is lack of control, depression, anxiety, and loneliness.{{Cite web |url=https://www.nationaleatingdisorders.org/factors-may-contribute-eating-disorders |title=Factors That May Contribute to Eating Disorders |work=National Eating Disorders Association |access-date=1 March 2016 |url-status=live |archive-url=https://web.archive.org/web/20160303114226/http://www.nationaleatingdisorders.org/factors-may-contribute-eating-disorders |archive-date=3 March 2016 |df=dmy-all}} People with anorexia are, in general, highly perfectionistic{{cite journal |vauthors=Halmi KA, Sunday SR, Strober M, Kaplan A, Woodside DB, Fichter M, Treasure J, Berrettini WH, Kaye WH |title=Perfectionism in anorexia nervosa: variation by clinical subtype, obsessionality, and pathological eating behavior |journal=American Journal of Psychiatry |volume=157 |issue=11 |pages=1799–1805 |date=November 2000 |pmid=11058477 |doi=10.1176/appi.ajp.157.11.1799}} and most have obsessive compulsive personality traits{{cite journal |vauthors=Anderluh MB, Tchanturia K, Rabe-Hesketh S, Treasure J |title=Childhood obsessive-compulsive personality traits in adult women with eating disorders: defining a broader eating disorder phenotype |journal=American Journal of Psychiatry |volume=160 |issue=2 |pages=242–247 |date=February 2003 |pmid=12562569 |doi=10.1176/appi.ajp.160.2.242}} which may facilitate sticking to a restricted diet.{{Cite web |title=Anorexia Nervosa |website=Mayo Clinic |url=https://www.mayoclinic.org/diseases-conditions/anorexia-nervosa/symptoms-causes/syc-20353591 |archive-url= |archive-date=}} It has been suggested that patients with anorexia are rigid in their thought patterns, and place a high level of importance upon being thin.{{cite journal |vauthors=Flett GL, Newby J, Hewitt PL, Persaud C |title=Perfectionistic automatic thoughts, trait perfectionism, and bulimic automatic thoughts in young women. |journal=Journal of Rational-Emotive & Cognitive-Behavior Therapy |date=September 2011 |volume=29 |issue=3 |pages=192–206 |doi=10.1007/s10942-011-0135-3 |s2cid=144731404}}{{cite journal |vauthors=Garner DM, Bemis KM |title=A cognitive-behavioral approach to anorexia nervosa. |date=June 1982 |volume=6 |issue=2 |pages=123–150 |doi=10.1007/BF01183887 |s2cid=10469356 |journal=Cognitive Therapy and Research}} In the context of anorexia nervosa, this cognitive rigidity refers to the diminished ability to adapt one's behavioral approaches in response to changing circumstances. This weaker cognitive flexibility is a result of neurobiological factors, such as structural differences in prefrontal cortex connectivity, that contribute to the persistence of anorexic behaviors.{{Cite journal |last1=Brockmeyer |first1=Timo |last2=Febry |first2=Hagen |last3=Leiteritz-Rausch |first3=Anna |last4=Wünsch-Leiteritz |first4=Wally |last5=Leiteritz |first5=Andreas |last6=Friederich |first6=Hans-Christoph |date=2022-02-15 |title=Cognitive flexibility, central coherence, and quality of life in anorexia nervosa |journal=Journal of Eating Disorders |volume=10 |issue=1 |pages=22 |doi=10.1186/s40337-022-00547-4 |doi-access=free |pmid=35168670 |pmc=8845392 |issn=2050-2974}}{{Cite journal |last1=Kidd |first1=Amelia |last2=Steinglass |first2=Joanna |date=2012-08-01 |title=What can Cognitive Neuroscience Teach us about Anorexia Nervosa? |journal=Current Psychiatry Reports |language=en |volume=14 |issue=4 |pages=415–420 |doi=10.1007/s11920-012-0285-8 |issn=1535-1645 |pmc=3410050 |pmid=22660896}}

Although the prevalence rates vary greatly, between 37% and 100%,{{cite journal |vauthors=Tagay S, Schlottbohm E, Reyes-Rodriguez ML, Repic N, Senf W |title=Eating disorders, trauma, PTSD, and psychosocial resources |journal=Eating Disorders |volume=22 |issue=1 |pages=33–49 |date=January 2014 |pmid=24365526 |pmc=3966425 |doi=10.1080/10640266.2014.857517}} there appears to be an association between traumatic events and eating disorder diagnosis.{{cite journal |vauthors=Reyes-Rodríguez ML, Von Holle A, Ulman TF, Thornton LM, Klump KL, Brandt H, Crawford S, Fichter MM, Halmi KA, Huber T, Johnson C, Jones I, Kaplan AS, Mitchell JE, Strober M, Treasure J, Woodside DB, Berrettini WH, Kaye WH, Bulik CM |title=Posttraumatic stress disorder in anorexia nervosa |journal=Psychosomatic Medicine |volume=73 |issue=6 |pages=491–497 |date=July 2011 |pmid=21715295 |pmc=3132652 |doi=10.1097/PSY.0b013e31822232bb}} Approximately 72% of individuals with anorexia report experiencing a traumatic event prior to the onset of eating disorder symptoms, with binge-purge subtype reporting the highest rates. There are many traumatic events that have been identified as possible risk factors for the development of anorexia, the first of which was childhood sexual abuse.{{cite journal |vauthors=Malecki J, Rhodes P, Ussher J |title=Childhood trauma and anorexia nervosa: from body image to embodiment |journal=Health Care for Women International |volume=39 |issue=8 |pages=936–951 |date=August 2018 |pmid=30152723 |doi=10.1080/07399332.2018.1492268 |s2cid=205580678}}

The prevalence of post-traumatic stress disorder among anorexia nervosa patients ranges from 4% to 24%. A complicated symptom profile develops when trauma and anorexia meld; the bodily experience of the individual is changed and intrusive thoughts and sensations may be experienced. Traumatic events can lead to intrusive and obsessive thoughts, and the symptom of anorexia that has been most closely linked to a PTSD diagnosis is increased obsessive thoughts pertaining to food. Similarly, impulsivity is linked to the purge and binge-purge subtypes of anorexia, trauma, and PTSD. Emotional trauma (e.g., invalidation, chaotic family environment in childhood) may lead to difficulty with emotions, particularly the identification of and how physical sensations contribute to the emotional response.

When trauma is perpetrated on an individual, it can lead to feelings of not being safe within their own body. Both physical and sexual abuse can lead to an individual seeing their body as belonging to an "other" and not to the "self". Individuals who feel as though they have no control over their bodies due to trauma may use food as a means of control because the choice to eat is an unmatched expression of control. By controlling the intake of food, individuals can decide when and how much they eat. Individuals, particularly children experiencing abuse, may feel a loss of control over their life, circumstances, and their own bodies. Particularly sexual abuse, but also physical abuse, can make individuals feel that the body is not a safe place and an object over which another has control. Starvation, in the case of anorexia, may also lead to reduction in the body as a sexual object, making starvation a solution. Restriction may also be a means by which the pain an individual is experiencing can be communicated.

Anorexia nervosa has been increasingly diagnosed since 1950;{{cite journal |vauthors= |title=Eating disorders and culture |journal=The Harvard Mental Health Letter |volume=20 |issue=9 |pages=7 |date=March 2004 |pmid=15044128}} the increase has been linked to vulnerability and internalization of body ideals.{{cite journal |vauthors=Herpertz-Dahlmann B, Bühren K, Remschmidt H |title=Growing up is hard: mental disorders in adolescence |journal=Deutsches Ärzteblatt International |volume=110 |issue=25 |pages=432–4399; quiz 440 |date=June 2013 |pmid=23840288 |pmc=3705204 |doi=10.3238/arztebl.2013.0432}} People in professions where there is a particular social pressure to be thin (such as models and dancers) were more likely to develop anorexia,{{Citation |vauthors=Francisco R |title=Body Image, Eating, and Weight |chapter=Studies on Body Image, Eating, and Weight in Models, Dancers, and Aesthetic Athletes |date=2018 |pages=401–411 |veditors=Cuzzolaro M, Fassino S |publisher=Springer International Publishing |language=en |doi=10.1007/978-3-319-90817-5_29 |isbn=978-3-319-90817-5 |hdl=10400.14/33058 |s2cid=150323306 |hdl-access=free}} and those with anorexia have much higher contact with cultural sources that promote weight loss.{{Cite book |vauthors=Becker AE |chapter=Sociocultural influences on body image and eating disturbance |chapter-url=https://books.google.com/books?id=2cI9DwAAQBAJ&q=anorexia+nervosa+culture+influence&pg=PA127 |url=https://books.google.com/books?id=2cI9DwAAQBAJ&q=anorexia+nervosa+culture+influence&pg=PA127 |veditors=Brownell KD, Walsh BT |title=Eating Disorders and Obesity: A Comprehensive Handbook |edition=Third |publisher=Guilford Publications |year=2018 |isbn=978-1-4625-3609-2 |pages=127–133 |language=en}} Internet usage heavily leads to deep societal practices of the upkeep of slender body types. Thus leading many to have symptoms of body dissatisfaction and low body image satisfaction. This trend can also be observed for people who partake in certain sports, such as jockeys and wrestlers.{{cite book |vauthors=Anderson-Fye EP, Becker AE |date=2004 |chapter=Sociocultural Aspects of Eating Disorders |pages=565–589 |title=Handbook of Eating Disorders and Obesity |veditors=Thompson KJ |location=Hoboken, NJ |publisher=John Wiley & Sons |isbn=978-0-471-23073-1}} There is a higher incidence and prevalence of anorexia nervosa in sports with an emphasis on aesthetics, where low body fat is advantageous, and sports in which one has to make weight for competition.{{cite journal |vauthors=Baum A |title=Eating disorders in the male athlete |journal=Sports Medicine |volume=36 |issue=1 |pages=1–6 |year=2006 |pmid=16445307 |doi=10.2165/00007256-200636010-00001 |url=http://www.sportsnutritionworkshop.com/Files/27.SPNT.pdf |url-status=live |s2cid=15296296 |df=dmy-all |archive-url=https://web.archive.org/web/20150604224524/http://www.sportsnutritionworkshop.com/Files/27.SPNT.pdf |archive-date=4 June 2015}} Family group dynamics can play a role in the perpetuation of anorexia including negative expressed emotion in overprotective families where blame is frequently experienced among its members.{{cite journal |vauthors=Kyriacou O, Treasure J, Schmidt U |title=Expressed emotion in eating disorders assessed via self-report: an examination of factors associated with expressed emotion in carers of people with anorexia nervosa in comparison to control families |journal=The International Journal of Eating Disorders |volume=41 |issue=1 |pages=37–46 |date=January 2008 |pmid=17922532 |doi=10.1002/eat.20469 |doi-access=free}}{{cite journal |vauthors=Yager J |title=Managing Patients With Severe and Enduring Anorexia Nervosa: When Is Enough, Enough? |journal=The Journal of Nervous and Mental Disease |volume=208 |issue=4 |pages=277–282 |date=April 2020 |pmid=32221180 |doi=10.1097/NMD.0000000000001124 |s2cid=209342890}}{{Cite web |url=http://psychiatric-disorders.com/eating-disorders/eating-disorders-anorexia-causes/ |title=Eating Disorders Anorexia Causes {{!}} Eating Disorders |work=Psychiatric Disorders and Mental Health Issues |language=en-US |date=13 June 2014 |access-date=1 March 2016 |url-status=live |archive-url=https://web.archive.org/web/20160307121722/http://psychiatric-disorders.com/eating-disorders/eating-disorders-anorexia-causes/ |archive-date=7 March 2016 |df=dmy-all}} In the face of constant pressure to be thin, often perpetuated by teasing and bullying, feelings of low self-esteem and self-worth can arise, including the perception that one is not "deserving" of food.

Persistent exposure to media that presents thin ideals may constitute a risk factor for body dysmorphia, leading to the development of anorexia nervosa. Western cultures that favor thin bodies as the beauty standard often have higher rates of anorexia nervosa.{{cite journal |vauthors=Simpson KJ |title=Anorexia nervosa and culture |journal=Journal of Psychiatric and Mental Health Nursing |volume=9 |issue=1 |pages=65–71 |date=February 2002 |pmid=11896858 |doi=10.1046/j.1351-0126.2001.00443.x}} Media sources such as magazines, television shows, and social media can contribute to body dissatisfaction and disordered eating globally, by emphasizing slimness rooted in Western ideals.{{cite journal |vauthors=Spettigue W, Henderson KA |title=Eating disorders and the role of the media |journal=The Canadian Child and Adolescent Psychiatry Review |volume=13 |issue=1 |pages=16–19 |date=February 2004 |pmid=19030149 |pmc=2533817}} Among magazines popular with people aged 18 to 24, those with a predominantly male audience were more likely to feature advertisements and articles focused on body shape in relation to body culture rather than promoting healthy diet.{{cite journal |vauthors=Labre MP |title=Adolescent boys and the muscular male body ideal |journal=The Journal of Adolescent Health |volume=30 |issue=4 |pages=233–242 |date=April 2002 |pmid=11927235 |doi=10.1016/S1054-139X(01)00413-X}} In addition to the direct effect of media on female body perception, media indirectly affects female body image through giving men a false perception of what a female body is meant to look like. Body dissatisfaction and internalization of body ideals are risk factors for anorexia nervosa that threaten the health of both male and female populations, with a predominant focus on women.{{cite journal |vauthors=Izydorczyk B, Sitnik-Warchulska K |title=Sociocultural Appearance Standards and Risk Factors for Eating Disorders in Adolescents and Women of Various Ages |journal=Frontiers in Psychology |volume=9 |pages=429 |date=29 March 2018 |pmid=29651268 |pmc=5885084 |doi=10.3389/fpsyg.2018.00429 |doi-access=free}}

Another online aspect contributing to higher rates of eating disorders such as anorexia nervosa are websites and communities on social media that stress the importance attaining the "ideal" body. These communities promote anorexia nervosa through the use of religious metaphors, lifestyle demonstrations, and photo galleries or quotes meant to motivate the individual's pursuit of thinness (commonly referred to as "thinspiration," "bone-spiration,"{{Cite journal |last1=Suhag |first1=Khushi |last2=Rauniyar |first2=Shyambabu |date=2024-04-21 |title=Social Media Effects Regarding Eating Disorders and Body Image in Young Adolescents |journal=Cureus |volume=16 |issue=4 |pages=e58674 |language=en |doi=10.7759/cureus.58674 |doi-access=free |issn=2168-8184 |pmc=11103119 |pmid=38770510}} and "fitspiration").{{cite book |last1=Drenten |first1=Jenna |last2=Gurrieri |first2=Lauren |title=Crossing the #BIKINIBRIDGE: Exploring the Role of Social Media in Propagating Body Image Trends |date=2018 |publisher=Routledge |location=New York, NY |isbn=9781138052550 |edition=1st |url=https://books.google.com/books?id=TlgPEAAAQBAJ&dq=body+trends+social+media&pg=PA49 |access-date=March 15, 2024}}{{cite journal |vauthors=Norris ML, Boydell KM, Pinhas L, Katzman DK |title=Ana and the Internet: a review of pro-anorexia websites |journal=The International Journal of Eating Disorders |volume=39 |issue=6 |pages=443–447 |date=September 2006 |pmid=16721839 |doi=10.1002/eat.20305 |s2cid=29355957}} These pro-anorexia websites reinforce internalization of body ideals and the importance of their attainment.

Cultural attitudes towards body image, beauty, and health also significantly impact the incidence of anorexia nervosa. There is a stark contrast between Western societies that idolize slimness and certain Eastern traditions that worship gods depicted with larger bodies,{{Cite journal |last=Lee |first=Sing |date=January 1996 |title=Reconsidering the status of anorexia nervosa as a western culture-bound syndrome |url=https://linkinghub.elsevier.com/retrieve/pii/0277953695000747 |journal=Social Science & Medicine |language=en |volume=42 |issue=1 |pages=21–34 |doi=10.1016/0277-9536(95)00074-7 |pmid=8745105}} and these varying cultural norms have varying influences on eating behaviors, self-perception, and anorexia in their respective cultures. For example, despite the fact that "fat phobia", or a fear of fat, is a key diagnostic criteria of anorexia by the DSM-5, anorexic patients in Asia rarely display this trait, as deep-rooted cultural values in Asian cultures praise larger bodies.{{Cite journal |last1=Demarque |first1=Mélissa |last2=Guzman |first2=Gabriela |last3=Morrison |first3=Elodie |last4=Ahovi |first4=Jonathan |last5=Moro |first5=Marie Rose |last6=Blanchet-Collet |first6=Corinne |date=April 2015 |title=Anorexia nervosa in a girl of Chinese origin: Psychological, somatic and transcultural factors |url=http://journals.sagepub.com/doi/10.1177/1359104513514067 |journal=Clinical Child Psychology and Psychiatry |language=en |volume=20 |issue=2 |pages=276–288 |doi=10.1177/1359104513514067 |pmid=24363225 |s2cid=13036347 |issn=1359-1045}} Fat phobia appears to be intricately linked to Western culture, encompassing how various cultural perceptions impact anorexia in various ways. It calls on the need for greater, diverse cultural consideration when looking at the diagnosis and experience of anorexia. For instance, in a cross-sectional study done on British South Asian adolescent English adolescent anorexia patients, it was found that both patients' symptom profiles differed. South Asians were less likely to exhibit fat-phobia as a symptom versus their English counterparts, instead exhibiting loss of appetite. Patients usually attributed their restricted food intake to somatic symptoms such as bloating, stomach pain, or lack of appetite.{{Cite journal |last1=Pike |first1=Kathleen M. |last2=Dunne |first2=Patricia E. |date=2015-09-17 |title=The rise of eating disorders in Asia: a review |journal=Journal of Eating Disorders |volume=3 |issue=1 |pages=33 |doi=10.1186/s40337-015-0070-2 |doi-access=free |issn=2050-2974 |pmc=4574181 |pmid=26388993}} However, both kinds of patients had distorted body images, implying the possibility of disordered eating and highlighting the need for cultural sensitivity when diagnosing anorexia.{{Cite journal|last1=Tareen |first1=Amina |last2=Hodes |first2=Matthew |last3=Rangel |first3=Luiza |date=February 2005 |title=Non-fat-phobic anorexia nervosa in British South Asian adolescents |url=https://onlinelibrary.wiley.com/doi/10.1002/eat.20080 |journal=International Journal of Eating Disorders |language=en |volume=37 |issue=2 |pages=161–165 |doi=10.1002/eat.20080 |pmid=15732077 |issn=0276-3478}} Collectivist and individualistic values also play a role in the manifestation of symptoms. Patients in China are more likely to display denial or minimization of symptoms since they are culturally encouraged to use conceal their symptoms to preserve group harmony.{{Cite journal |last1=Agüera |first1=Zaida |last2=Brewin |first2=Nicola |last3=Chen |first3=Jue |last4=Granero |first4=Roser |last5=Kang |first5=Qing |last6=Fernandez-Aranda |first6=Fernando |last7=Arcelus |first7=Jon |date=2017-03-16 |title=Eating symptomatology and general psychopathology in patients with anorexia nervosa from China, UK and Spain: A cross-cultural study examining the role of social attitudes |journal=PLOS ONE |volume=12 |issue=3 |pages=e0173781 |doi=10.1371/journal.pone.0173781 |doi-access=free |pmid=28301566 |pmc=5354396 |bibcode=2017PLoSO..1273781A |issn=1932-6203}}

These cultural differences are further empathized in research on the Caribbean island of Curaçao which revealed a substantially lower overall incidence of anorexia nervosa than that observed in the United States and Western Europe.  Specifically, no cases were identified among the majority Black population, while the minority mixed and white population showed incidence rates similar to those in Western countries. This disparity highlights potential cultural variations in the development and presentation of anorexia nervosa, particularly when comparing Black women in Curaçao to those exposed to Western cultural influences.{{Cite journal |last=Hoek |first=Hans Wijbrand |date=July 2006 |title=Incidence, prevalence and mortality of anorexia nervosa and other eating disorders |url=https://journals.lww.com/co-psychiatry/abstract/2006/07000/incidence,_prevalence_and_mortality_of_anorexia.10.aspx |journal=Current Opinion in Psychiatry |language=en-US |volume=19 |issue=4 |pages=389–394 |doi=10.1097/01.yco.0000228759.95237.78 |pmid=16721169 |issn=0951-7367}}

Notably, although these cultural distinctions persist, modernization and globalization slowly homogenize these attitudes. Anorexia is increasingly tied to the pressures of a global culture that celebrates Western ideals of thinness. The spread of Western media, fashion, and lifestyle ideals across the globe has begun to shift perceptions and standards of beauty in diverse cultures, contributing to a rise in the incidence of anorexia in places they were once rare.{{Cite journal |last1=Kim |first1=Youl-Ri |last2=Nakai |first2=Yoshikatsu |last3=Thomas |first3=Jennifer J. |date=January 2021 |title=Introduction to a special issue on eating disorders in Asia |url=https://onlinelibrary.wiley.com/doi/10.1002/eat.23444 |journal=International Journal of Eating Disorders |language=en |volume=54 |issue=1 |pages=3–6 |doi=10.1002/eat.23444 |pmid=33340374 |s2cid=229325699 |issn=0276-3478}} Anorexia, once primarily associated with Western culture, seems more than ever to be linked to the cultures of modernity and globalization.{{Citation needed|date=February 2025}}

However, unique cultural-specific phenotypes of disordered eating emerged prior to Western influence. For example, restrictive eating patterns were found in Japan as early as the 18th century and fewer reports of eating disorders were found between 1868 and 1944, when rapid Westernization occurred.{{Cite journal |last1=Nakai |first1=Yoshikatsu |last2=Nin |first2=Kazuko |last3=Goel |first3=Neha J. |date=2021 |title=The changing profile of eating disorders and related sociocultural factors in Japan between 1700 and 2020: A systematic scoping review |journal=International Journal of Eating Disorders |language=en |volume=54 |issue=1 |pages=40–53 |doi=10.1002/eat.23439 |issn=1098-108X |pmc=8204748 |pmid=33336841}} Sex-specific stressors and cultural dynamics could be implicated in this independent development of anorexia nervosa symptomology.

Evidence from physiological, pharmacological and neuroimaging studies suggest serotonin (also called 5-HT) may play a role in anorexia. While acutely ill, metabolic changes may produce a number of biological findings in people with anorexia that are not necessarily causative of the anorexic behavior. For example, abnormal hormonal responses to challenges with serotonergic agents have been observed during acute illness, but not recovery. Nevertheless, increased cerebrospinal fluid concentrations of 5-hydroxyindoleacetic acid (a metabolite of serotonin), and changes in anorectic behavior in response to acute tryptophan depletion (tryptophan is a metabolic precursor to serotonin) support a role in anorexia. The activity of the 5-HT_2A receptors has been reported to be lower in patients with anorexia in a number of cortical regions, evidenced by lower binding potential of this receptor as measured by PET or SPECT, independent of the state of illness. While these findings may be confounded by comorbid psychiatric disorders, taken as a whole they indicate serotonin in anorexia.{{cite journal |vauthors=Kaye WH, Frank GK, Bailer UF, Henry SE, Meltzer CC, Price JC, Mathis CA, Wagner A |title=Serotonin alterations in anorexia and bulimia nervosa: new insights from imaging studies |journal=Physiology & Behavior |volume=85 |issue=1 |pages=73–81 |date=May 2005 |pmid=15869768 |doi=10.1016/j.physbeh.2005.04.013 |s2cid=25676759}}{{cite journal |vauthors=Kaye WH, Bailer UF, Frank GK, Wagner A, Henry SE |title=Brain imaging of serotonin after recovery from anorexia and bulimia nervosa |journal=Physiology & Behavior |volume=86 |issue=1–2 |pages=15–17 |date=September 2005 |pmid=16102788 |doi=10.1016/j.physbeh.2005.06.019 |s2cid=17250708}} These alterations in serotonin have been linked to traits characteristic of anorexia such as obsessiveness, anxiety, and appetite dysregulation.

Neuroimaging studies investigating the functional connectivity between brain regions have observed a number of alterations in networks related to cognitive control, introspection, and sensory function. Alterations in networks related to the dorsal anterior cingulate cortex may be related to excessive cognitive control of eating related behaviors. Similarly, altered somatosensory integration and introspection may relate to abnormal body image.{{cite journal |vauthors=Gaudio S, Wiemerslage L, Brooks SJ, Schiöth HB |title=A systematic review of resting-state functional-MRI studies in anorexia nervosa: Evidence for functional connectivity impairment in cognitive control and visuospatial and body-signal integration |journal=Neuroscience and Biobehavioral Reviews |volume=71 |pages=578–589 |date=December 2016 |pmid=27725172 |doi=10.1016/j.neubiorev.2016.09.032 |doi-access=free}} A review of functional neuroimaging studies reported reduced activations in "bottom up" limbic region and increased activations in "top down" cortical regions which may play a role in restrictive eating.{{cite journal |vauthors=Fuglset TS, Landrø NI, Reas DL, Rø Ø |title=Functional brain alterations in anorexia nervosa: a scoping review |journal=Journal of Eating Disorders |volume=4 |pages=32 |date=2016 |pmid=27933159 |pmc=5125031 |doi=10.1186/s40337-016-0118-y |doi-access=free}}

Compared to controls, people who have recovered from anorexia show reduced activation in the reward system in response to food, and reduced correlation between self reported liking of a sugary drink and activity in the striatum and anterior cingulate cortex. Increased binding potential of ¹¹C radiolabelled raclopride in the striatum, interpreted as reflecting decreased endogenous dopamine due to competitive displacement, has also been observed.{{cite book |vauthors=Kaye WH, Wagner A, Fudge JL, Paulus M |chapter=Neurocircuitry of Eating Disorders |veditors=Adan RA, Kaye WH |title=Behavioral Neurobiology of Eating Disorders: 6 |series=Current Topics in Behavioral Neurosciences |date=2011 |publisher=Springer Berlin Heidelberg |pages=59–80 |isbn=978-3-642-15131-6}}

Structural neuroimaging studies have found global reductions in both gray matter and white matter, as well as increased cerebrospinal fluid volumes. Regional decreases in the left hypothalamus, left inferior parietal lobe, right lentiform nucleus and right caudate have also been reported{{cite journal |vauthors=Titova OE, Hjorth OC, Schiöth HB, Brooks SJ |title=Anorexia nervosa is linked to reduced brain structure in reward and somatosensory regions: a meta-analysis of VBM studies |journal=BMC Psychiatry |volume=13 |pages=110 |date=April 2013 |pmid=23570420 |pmc=3664070 |doi=10.1186/1471-244X-13-110 |doi-access=free}} in acutely ill patients. However, these alterations seem to be associated with acute malnutrition and largely reversible with weight restoration, at least in nonchronic cases in younger people.{{cite journal |vauthors=King JA, Frank GK, Thompson PM, Ehrlich S |title=Structural Neuroimaging of Anorexia Nervosa: Future Directions in the Quest for Mechanisms Underlying Dynamic Alterations |journal=Biological Psychiatry |volume=83 |issue=3 |pages=224–234 |date=February 2018 |pmid=28967386 |pmc=6053269 |doi=10.1016/j.biopsych.2017.08.011}} In contrast, some studies have reported increased orbitofrontal cortex volume in currently ill and in recovered patients, although findings are inconsistent. Reduced white matter integrity in the fornix has also been reported.{{cite journal |vauthors=Frank GK |title=Advances from neuroimaging studies in eating disorders |journal=CNS Spectrums |volume=20 |issue=4 |pages=391–400 |date=August 2015 |pmid=25902917 |pmc=4989857 |doi=10.1017/S1092852915000012}}

A diagnostic assessment includes the person's current circumstances, biographical history, current symptoms, and family history. The assessment also includes a mental state examination, which is an assessment of the person's current mood and thought content, focusing on views on weight and patterns of eating.

Anorexia nervosa is classified under the Feeding and Eating Disorders in the latest revision of the Diagnostic and Statistical Manual of Mental Disorders (DSM 5). There is no specific BMI cut-off that defines low weight required for the diagnosis of anorexia nervosa.{{cite journal |vauthors=Mitchell JE, Peterson CB |date=April 2020 |title=Anorexia Nervosa |journal=The New England Journal of Medicine |volume=382 |issue=14 |pages=1343–1351 |doi=10.1056/NEJMcp1803175 |pmid=32242359 |s2cid=214769639}}

The diagnostic criteria for anorexia nervosa (all of which needing to be met for diagnosis) are:{{Cite web |date=June 2016|title=DSM-5 Changes: Implications for Child Serious Emotional Disturbance|url=https://www.samhsa.gov/data/sites/default/files/NSDUH-DSM5ImpactChildSED-2016.pdf |access-date=2021-09-17|website=Substance Abuse and Mental Health Services Administration|page=48 (Table 19, DSM-IV to DSM-5 Anorexia Nervosa Comparison)|language=en|via=}}

• Restriction of energy intake relative to requirements leading to a low body weight. (Criterion A)
• Intense fear of gaining weight or persistent behaviors that interfere with gaining weight. (Criterion B)
• Disturbance in the way a person's weight or body shape is experienced or a lack of recognition about the risks of the low body weight. (Criterion C)

Relative to the previous version of the DSM (DSM-IV-TR), the 2013 revision (DSM5) reflects changes in the criteria for anorexia nervosa. Most notably, the amenorrhea (absent period) criterion was removed.{{cite web|url=http://www.dsm5.org/documents/eating%20disorders%20fact%20sheet.pdf |title=Feeding and eating disorders |publisher=American Psychiatric Publishing |date=2013 |access-date=9 April 2015 |url-status=dead |archive-url=https://web.archive.org/web/20150501013951/http://www.dsm5.org/Documents/Eating%20Disorders%20Fact%20Sheet.pdf |archive-date=1 May 2015}}{{cite journal |vauthors=Estour B, Galusca B, Germain N |title=Constitutional thinness and anorexia nervosa: a possible misdiagnosis? |journal=Frontiers in Endocrinology |volume=5 |pages=175 |year=2014 |pmid=25368605 |pmc=4202249 |doi=10.3389/fendo.2014.00175 |doi-access=free}} Amenorrhea was removed for several reasons: it does not apply to males, it is not applicable for females before the age of menstruation, during or after the menopause, or women of any age taking birth control. Additionally, some women who meet the other criteria for AN still report some menstrual activity.

There are two subtypes of AN:{{cite journal |vauthors=Peat C, Mitchell JE, Hoek HW, Wonderlich SA |title=Validity and utility of subtyping anorexia nervosa |journal=The International Journal of Eating Disorders |volume=42 |issue=7 |pages=590–594 |date=November 2009 |pmid=19598270 |pmc=2844095 |doi=10.1002/eat.20717}}

• Restrictive Type: In the most recent months leading up to the evaluation, the patient has not engaged in binging and purging via laxative or diuretic abuse, enemas, or self-induced vomiting. The weight loss accomplished in this patient is mainly through the use of one or more of the following methods: fasting, dieting, and excessive exercise.{{Citation |title=Other Mental Disorders |work=Diagnostic and Statistical Manual of Mental Disorders, 5th Edition |date=2013 |url=https://doi.org/10.1176/appi.books.9780890425596.529303 |access-date=2024-12-17 |publisher=American Psychiatric Publishing, Inc |doi=10.1176/appi.books.9780890425596.529303 |isbn=978-0-89042-559-6}}
• Binge-eating / Purging Type: In the last few months, the patient has recurrently engaged in binge-purge cycles.

The use of the body mass index in the diagnosis of eating disorders has been controversial, largely owing to its oversimplification of health and failure to take into account complicating factors such as body composition or the initial bodyweight of the patient prior to the onset of AN.{{Cite journal |last=Mattar |first=Lama |date=March 8, 2011 |title=Anorexia nervosa and nutritional assessment: contribution of body composition measurements |url= |journal=Nutrition Research Reviews |volume=24 |issue=1 |pages=39–45|doi=10.1017/S0954422410000284 |pmid=21382223}} As such, the DSM-5 does not have a strict BMI cutoff for the diagnosis of anorexia nervosa,{{Cite journal |last1=Himmerich |first1=Hubertus |last2=Treasure |first2=Janet |date=1 April 2024 |title=Anorexia nervosa: diagnostic, therapeutic, and risk biomarkers in clinical practice |journal=Trends in Molecular Medicine |series=Special issue: Eating disorders |volume=30 |issue=4 |pages=350–360 |doi=10.1016/j.molmed.2024.01.002 |pmid=38331700 |issn=1471-4914 |doi-access=free}} but it nevertheless uses BMI to establish levels of severity, which it states as follows:{{Cite book |title=Primary Care, Second Edition: An Interprofessional Perspective |url=https://books.google.com/books?id=jJCKBQAAQBAJ&q=anorexia%20nervosa%20%20body%20mass%20index%20%20DSM-v%20levels%20of%20severity&pg=PA826 |publisher=Springer Publishing Company |date=12 November 2014 |access-date=9 April 2015 |isbn=978-0-8261-7147-4 |vauthors=Singleton JK}}

• Mild: BMI of greater than 17
• Moderate: BMI of 16–16.99
• Severe: BMI of 15–15.99
• Extreme: BMI of less than 15

Medical tests to check for signs of physical deterioration in anorexia nervosa may be performed by a general physician or psychiatrist.

Physical examination:

• Blinded weight: The patient will strip and put on a surgical gown alone. The patient will step backwards onto the scale as the healthcare provider blocks the reading from the patient's line of vision.{{Citation needed|date=February 2025}}
• Orthostatic vitals: The patient lies completely flat for five minutes, and then, the medical provider measures the patient's blood pressure and heart rate. The patient stands up and stays stationary for two minutes. Then, the blood pressure and heart rate are assessed again, making note of any patient symptoms upon standing like dizziness. According to the College of Family Physicians of Canada, a change in orthostatic heart rate greater than 20 beats/minute or a change in orthostatic blood pressure greater than 10mmHg can warrant admission for an adolescent.{{Cite journal |last=Khalifa |first=Isabelle |date=February 2019 |title=Anorexia nervosa requiring admission in adolescents |journal=L'Anorexie mentale nécessitant une hospitalisation chez les adolescents |volume=65 |issue=2 |pages=107–108|pmid=30765357 |pmc=6515507}}
• Examination of hands and arms for brittle nails, Russell's sign, swollen joints, lanugo, and self harm.{{Cite web |title=Physical examination in Anorexia nervosa |url=http://www.simplypsychiatry.co.uk/sitebuildercontent/sitebuilderfiles/physicalexaminationinanorexianervosa.pdf}}
• Auscultation of the chest for rubs, gallops, thrills, murmurs, and apex beat.
• Examination of the face for puffiness, dental decay, swollen parotid glands, and conjunctival hemorrhage.

Blood tests:

• Complete blood count (CBC): a test of the white blood cells, red blood cells and platelets used to assess the presence of various disorders such as leukocytosis, leukopenia, thrombocytosis and anemia which may result from malnutrition.{{cite web |title=CBC blood test |url=https://www.nlm.nih.gov/medlineplus/ency/article/003642.htm |work=MedlinePlus |publisher=U.S. National Library of Medicine |access-date=31 May 2013 |url-status=live |archive-url=https://web.archive.org/web/20130525021411/http://www.nlm.nih.gov/medlineplus/ency/article/003642.htm |archive-date=25 May 2013}}
• Chem-20: Chem-20, also known as SMA-20, is a group of twenty separate chemical tests performed on blood serum. Tests include protein and electrolytes such as potassium, chlorine and sodium, and tests specific to liver and kidney function.{{cite web |url=https://www.nlm.nih.gov/medlineplus/ency/article/003468.htm |title=Comprehensive metabolic panel |work=MedlinePlus |publisher=U.S. National Library of Medicine |archive-url=https://web.archive.org/web/20150405020539/http://www.nlm.nih.gov/medlineplus/ency/article/003468.htm |archive-date=5 April 2015 |access-date=4 February 2012}}
• Glucose tolerance test: Oral glucose tolerance test (OGTT) used to assess the body's ability to metabolize glucose. Can be useful in detecting various disorders such as diabetes, an insulinoma, Cushing's Syndrome, hypoglycemia and polycystic ovary syndrome.{{cite journal |vauthors=Lee H, Oh JY, Sung YA, Chung H, Cho WY |title=The prevalence and risk factors for glucose intolerance in young Korean women with polycystic ovary syndrome |journal=Endocrine |volume=36 |issue=2 |pages=326–332 |date=October 2009 |pmid=19688613 |doi=10.1007/s12020-009-9226-7 |s2cid=207361456}}
• Lipid profile: includes cholesterol (including total cholesterol, HDL and LDL) and triglycerides.{{cite web|url=http://www.maudsleyparents.org/images/lab_tests.pdf|title=Guide to Common Laboratory Tests for Eating Disorder Patients|website=Maudsleyparents.org|access-date=29 June 2022}}
• Serum cholinesterase test: a test of liver enzymes (acetylcholinesterase and pseudocholinesterase) useful as a test of liver function and to assess the effects of malnutrition.{{cite journal |vauthors=Montagnese C, Scalfi L, Signorini A, De Filippo E, Pasanisi F, Contaldo F |title=Cholinesterase and other serum liver enzymes in underweight outpatients with eating disorders |journal=The International Journal of Eating Disorders |volume=40 |issue=8 |pages=746–750 |date=December 2007 |pmid=17610252 |doi=10.1002/eat.20432}}
• Liver function tests: A series of tests used to assess liver function some of the tests are also used in the assessment of malnutrition, protein deficiency, kidney function, bleeding disorders, and Crohn's Disease.{{cite journal |vauthors=Narayanan V, Gaudiani JL, Harris RH, Mehler PS |title=Liver function test abnormalities in anorexia nervosa—cause or effect |journal=The International Journal of Eating Disorders |volume=43 |issue=4 |pages=378–381 |date=May 2010 |pmid=19424979 |doi=10.1002/eat.20690}}
• Luteinizing hormone (LH) response to gonadotropin-releasing hormone (GnRH): Tests the pituitary glands' response to GnRh, a hormone produced in the hypothalamus. Hypogonadism is often seen in anorexia nervosa cases.
• Creatine kinase (CK) test: measures the circulating blood levels of creatine kinase an enzyme found in the heart (CK-MB), brain (CK-BB) and skeletal muscle (CK-MM).{{cite journal |vauthors=Walder A, Baumann P |title=Increased creatinine kinase and rhabdomyolysis in anorexia nervosa |journal=The International Journal of Eating Disorders |volume=41 |issue=8 |pages=766–767 |date=December 2008 |pmid=18521917 |doi=10.1002/eat.20548}}
• Blood urea nitrogen (BUN) test: urea nitrogen is the byproduct of protein metabolism first formed in the liver then removed from the body by the kidneys. The BUN test is primarily used to test kidney function. A low BUN level may indicate the effects of malnutrition.{{cite web |url=https://www.nlm.nih.gov/medlineplus/ency/article/003474.htm |title=BUN – blood test |work=MedlinePlus |publisher=U.S. National Library of Medicine |archive-url=https://web.archive.org/web/20100409224427/http://www.nlm.nih.gov/medlineplus/ency/article/003474.htm |archive-date=9 April 2010 |date=26 January 2012 |access-date=4 February 2012}}
• BUN-to-creatinine ratio: A BUN to creatinine ratio is used to predict various conditions. A high BUN/creatinine ratio can occur in severe hydration, acute kidney failure, congestive heart failure, and intestinal bleeding. A low BUN/creatinine ratio can indicate a low protein diet, celiac disease, rhabdomyolysis, or cirrhosis of the liver.{{cite journal |vauthors=Sheridan AM, Bonventre JV |title=Cell biology and molecular mechanisms of injury in ischemic acute renal failure |journal=Current Opinion in Nephrology and Hypertension |volume=9 |issue=4 |pages=427–434 |date=July 2000 |pmid=10926180 |doi=10.1097/00041552-200007000-00015}}{{cite journal |vauthors=Nelsen DA |title=Gluten-sensitive enteropathy (celiac disease): more common than you think |journal=American Family Physician |volume=66 |issue=12 |pages=2259–2266 |date=December 2002 |pmid=12507163 |url=http://www.aafp.org/link_out?pmid=12507163}}
• Thyroid function tests: tests used to assess thyroid functioning by checking levels of thyroid-stimulating hormone (TSH), thyroxine (T4), and triiodothyronine (T3).{{cite journal |vauthors=Misra M, Klibanski A |date=2011 |title=The neuroendocrine basis of anorexia nervosa and its impact on bone metabolism |journal=Neuroendocrinology |volume=93 |issue=2 |pages=65–73 |doi=10.1159/000323771 |pmc=3214929 |pmid=21228564}}

Additional medical screenings:

• Urinalysis: a variety of tests performed on the urine used in the diagnosis of medical disorders, to test for substance abuse, and as an indicator of overall health{{cite web |date=26 January 2012 |title=Urinalysis |url=https://www.nlm.nih.gov/medlineplus/ency/article/003579.htm |archive-url=https://web.archive.org/web/20100404072220/http://www.nlm.nih.gov/medlineplus/ency/article/003579.htm |archive-date=4 April 2010 |access-date=4 February 2012 |work=MedlinePlus |publisher=U.S. National Library of Medicine}}
• Electrocardiogram (EKG or ECG): measures electrical activity of the heart. It can be used to detect various disorders such as hyperkalemia.{{cite journal |vauthors=Pepin J, Shields C |title=Advances in diagnosis and management of hypokalemic and hyperkalemic emergencies |journal=Emergency Medicine Practice |volume=14 |issue=2 |pages=1–17; quiz 17–8 |date=February 2012 |pmid=22413702}}
• Electroencephalogram (EEG): measures the electrical activity of the brain. It can be used to detect abnormalities such as those associated with pituitary tumors.{{cite web |url=https://www.nlm.nih.gov/medlineplus/ency/article/003931.htm |title=Electroencephalogram |work=Medline Plus |date=26 January 2012 |access-date=4 February 2012 |url-status=live |archive-url=https://web.archive.org/web/20120127151819/http://www.nlm.nih.gov/medlineplus/ency/article/003931.htm |archive-date=27 January 2012}}

{{Main|Differential diagnoses of anorexia nervosa}}

A variety of medical and psychological conditions have been misdiagnosed as anorexia nervosa; in some cases the correct diagnosis was not made for more than ten years.{{Citation needed|date=February 2025}}

The distinction between binge purging anorexia, bulimia nervosa and Other Specified Feeding or Eating Disorders (OSFED) is often difficult for non-specialist clinicians. A main factor differentiating binge-purge anorexia from bulimia is the gap in physical weight. Patients with bulimia nervosa are ordinarily at a healthy weight, or slightly overweight. Patients with binge-purge anorexia are commonly underweight.{{cite book |vauthors=Nolen-Hoeksema S |title=Abnormal Psychology |edition=Sixth |year=2014 |publisher=McGraw-Hill Education |location=New York |isbn=978-0-07-803538-8 |page=341 |chapter=Eating disorders}} Moreover, patients with the binge-purging subtype may be significantly underweight and typically do not binge-eat large amounts of food. In contrast, those with bulimia nervosa tend to binge large amounts of food. It is not unusual for patients with an eating disorder to "move through" various diagnoses as their behavior and beliefs change over time.

Treatment for people with anorexia nervosa should be individualized and tailored to each person's medical, psychological, and nutritional circumstances. Treating this condition with an interdisciplinary team is suggested so that the different health care professional specialties can help addresses the different challenges that can be associated with recovery. Treatment for anorexia typically involves a combination of medical, psychological interventions such as therapy, and nutritional interventions (diet) interventions. Hospitalization may also be needed in some cases, and the person requires a comprehensive medical assessment to help direct the treatment options. There is no conclusive evidence that any particular treatment approach for anorexia nervosa works better than others.{{cite journal |vauthors=Lock JD, Fitzpatrick KK |title=Anorexia nervosa |journal=BMJ Clinical Evidence |volume=2009 |date=March 2009 |pmid=19445758 |pmc=2907776}} In some clinical settings a specific body image intervention is performed to reduce body dissatisfaction and body image disturbance. Although restoring the person's weight is the primary task at hand, optimal treatment also includes and monitors behavioral change in the individual as well.

In general, treatment for anorexia nervosa aims to address three main areas:

• Restoring the person to a healthy weight;
• Treating the psychological disorders related to the illness;
• Reducing or eliminating behaviors or thoughts that originally led to the disordered eating.{{Cite web |author=National Institute of Mental Health |url=http://www.nimh.nih.gov/health/topics/eating-disorders/index.shtml |title=Eating disorders |access-date=23 March 2015 |url-status=dead |archive-url=https://web.archive.org/web/20150323185427/http://www.nimh.nih.gov/health/topics/eating-disorders/index.shtml |archive-date=23 March 2015}}

Psychological support, often in the form of cognitive-behavioral therapy (CBT), family-bases treatment, or psychotherapy aims to change distorted thoughts and behaviors around food, body image, and self-worth, with family-based therapy also being a key approach for younger patients.

Family-based treatment (FBT) may be more successful than individual therapy for adolescents with AN.{{cite journal |vauthors=Russell GF, Szmukler GI, Dare C, Eisler I |title=An evaluation of family therapy in anorexia nervosa and bulimia nervosa |journal=Archives of General Psychiatry |volume=44 |issue=12 |pages=1047–1056 |date=December 1987 |pmid=3318754 |doi=10.1001/archpsyc.1987.01800240021004 |df=dmy-all}} Various forms of family-based treatment have been proven to work in the treatment of adolescent AN including conjoint family therapy (CFT), in which the parents and child are seen together by the same therapist, and separated family therapy (SFT) in which the parents and child attend therapy separately with different therapists. Proponents of family therapy for adolescents with AN assert that it is important to include parents in the adolescent's treatment. The evidence supporting family based therapy for adults is weak and despite the evidence that it is effective and the primary choice for treatment in adolescents, there is no evidence it is helpful for adults.{{cite journal |vauthors=Blessitt E, Voulgari S, Eisler I |date=November 2015 |title=Family therapy for adolescent anorexia nervosa |journal=Current Opinion in Psychiatry |volume=28 |issue=6 |pages=455–460 |doi=10.1097/yco.0000000000000193 |pmid=26382158 |s2cid=33438815}}{{Cite journal |last1=Fisher |first1=Caroline A. |last2=Skocic |first2=Sonja |last3=Rutherford |first3=Kathleen A. |last4=Hetrick |first4=Sarah E. |date=2019-05-01 |title=Family therapy approaches for anorexia nervosa |journal=The Cochrane Database of Systematic Reviews |volume=2019 |issue=5 |pages=CD004780 |doi=10.1002/14651858.CD004780.pub4 |issn=1469-493X |pmc=6497182 |pmid=31041816}} A four- to five-year follow up study of the Maudsley family therapy, an evidence-based manualized model, showed full recovery at rates up to 90%.{{cite journal |vauthors=le Grange D, Eisler I |title=Family interventions in adolescent anorexia nervosa |journal=Child and Adolescent Psychiatric Clinics of North America |volume=18 |issue=1 |pages=159–173 |date=January 2009 |pmid=19014864 |doi=10.1016/j.chc.2008.07.004}} The Maudsley model of family therapy is problem focused, and the treatment targets re-establishing regular eating, weight restoration, and the reduction of illness behaviors like purging.{{cite journal |vauthors=Treasure J, Parker S, Oyeleye O, Harrison A |title=The value of including families in the treatment of anorexia nervosa |journal=European Eating Disorders Review |volume=29 |issue=3 |pages=393–401 |date=May 2021 |pmid=33351987 |pmc=8246805 |doi=10.1002/erv.2816}} The Maudsley model is split into three phases, with phase one focusing on the parents implementing weight restoration in the child; phase two transitioning control over food back to the individual at an age-appropriate level; and phase three focusing on other issues related to typical adolescent development (e.g., social and other psychological developments), and helps parents learn how to interact with their child. Although this model is recommended by the National Institute of Mental Health (NIMH),{{cite web |year=2011 |title=Eating Disorders |url=http://www.nimh.nih.gov/health/publications/eating-disorders/index.shtml |url-status=live |archive-url=https://web.archive.org/web/20131001083640/http://www.nimh.nih.gov/health/publications/eating-disorders/index.shtml |archive-date=1 October 2013 |access-date=29 September 2013 |publisher=National Institute of Mental Health |df=dmy-all}} critics claim that it has the potential to create power struggles in an intimate relationship and may disrupt equal partnerships.

Cognitive behavioral therapy (CBT) is useful in adolescents and adults with anorexia nervosa.{{Cite book |url=https://books.google.com/books?id=ao3hwH194ugC&q=cognitive%20behavioral%20therapy%20for%20anorexia%20nervosa&pg=PA146 |title=Cognitive Behavioural Therapy Explained |vauthors=Whitfield G, Davidson A |date=2007 |publisher=Radcliffe Publishing |isbn=978-1-85775-603-6 |access-date=9 April 2015}} One of the most known psychotherapy in the field is CBT-E, an enhanced cognitive-behavior therapy specifically focus to eating disorder psychopathology. Acceptance and commitment therapy is a third-wave cognitive-behavioral therapy which has shown promise in the treatment of AN.{{Cite book |url=https://books.google.com/books?id=wm3XBQAAQBAJ&q=acceptance%20and%20commitment%20therapy%20for%20anorexia%20nervosa&pg=PA410|title=Psychiatric Nursing |vauthors=Keltner NL, Steele D |date=6 August 2014 |publisher=Elsevier Health Sciences |isbn=978-0-323-29352-5 |access-date=9 April 2015}} Cognitive remediation therapy (CRT) is also used in treating anorexia nervosa.{{cite journal |vauthors=Tchanturia K, Lounes N, Holttum S |title=Cognitive remediation in anorexia nervosa and related conditions: a systematic review |journal=European Eating Disorders Review |volume=22 |issue=6 |pages=454–462 |date=November 2014 |pmid=25277720 |doi=10.1002/erv.2326}} Schema-Focused Therapy (a form of CBT) was developed by Dr. Jeffrey Young and is effective in helping patients identify origins and triggers for disordered eating.{{cite journal |title=An Interpretative Phenomenological Analysis of Schema Modes in a Single Case of Anorexia Nervosa: Part 1- Background, Method, and Child and Parent Modes |journal=Indo-Pacific Journal of Phenomenology |year=2017 |doi=10.1080/20797222.2017.1326728 |vauthors=Edwards DJ |volume=17 |pages=1–13 |s2cid=148977898 |doi-access=free}}

Psychotherapy for individuals with AN is challenging as they may value being thin and may seek to maintain control and resist change.{{cite book |title=Abnormal Psychology |vauthors=Nolen-Hoeksema S |date=2014 |publisher=McGraw-Hill Education |isbn=978-1-259-06072-4 |edition=Sixth |page=357}} Initially, developing a desire to change is fundamental.{{Cite book |url=https://books.google.com/books?id=3gmogQshI_MC&pg=PA94 |title=Handbook of Treatment for Eating Disorders |vauthors=Garner DM, Garfinkel PE |date=1 January 1997 |publisher=Guilford Press |isbn=978-1-57230-186-3 |language=en}} There is no strong evidence to suggest one type of psychotherapy over another for treating anorexia nervosa in adults or adolescents.{{Cite journal |last1=Hay |first1=Phillipa J |last2=Claudino |first2=Angélica M |last3=Touyz |first3=Stephen |last4=Abd Elbaky |first4=Ghada |date=2015-07-27 |editor-last=Cochrane Common Mental Disorders Group |title=Individual psychological therapy in the outpatient treatment of adults with anorexia nervosa |journal=Cochrane Database of Systematic Reviews |language=en |volume=2018 |issue=2 |pages=CD003909 |doi=10.1002/14651858.CD003909.pub2 |pmc=6491116 |pmid=26212713}}

Diet is the most essential factor to work on in people with anorexia nervosa, and must be tailored to each person's needs. Food variety is important when establishing meal plans as well as foods that are higher in energy density, especially in carbohydrates and dietary fat, which are easier for the undernourished body to break down.{{cite book |vauthors=Whitnet E, Rolfes SR |year=2011 |title=Understanding Nutrition |location=United States |publisher=Wadsworth Cengage Learning |isbn=978-1-133-58752-1 |page=255 |url=https://books.google.com/books?id=OQgLAAAAQBAJ&pg=SA8-PA19 |url-status=live |archive-url=https://web.archive.org/web/20151124102125/https://books.google.com/books?id=OQgLAAAAQBAJ&lpg=PP9&pg=SA8-PA19 |archive-date=24 November 2015}} Evidence of a role for zinc supplementation during refeeding is unclear. Dieticians work with the medical team to add dietary supplements like iron, every other day, or calcium.

Historically, practitioners have slowly increased calories at a measured pace from a starting point of around 1,200 kcal/day.{{cite journal |vauthors=Garber AK, Sawyer SM, Golden NH, Guarda AS, Katzman DK, Kohn MR, Le Grange D, Madden S, Whitelaw M, Redgrave GW |title=A systematic review of approaches to refeeding in patients with anorexia nervosa |journal=The International Journal of Eating Disorders |volume=49 |issue=3 |pages=293–310 |date=March 2016 |pmid=26661289 |pmc=6193754 |doi=10.1002/eat.22482}} However, as understanding of the process of weight restoration has improved, an approach that favors a higher starting point and a more rapid rate of increase has become increasingly common. In either approach, the end goal is typically in the range of 3,000 to 3,500 kcal/day.

After experiencing prolonged significant calorie deficits, people often undergo extreme hunger (hyperphagia). Once weight is regained in both fat and muscle mass, their hunger usually returns to normalized levels. This process of regaining weight takes longer for fat-free/muscle mass which leads to a "fat overshoot" or "overshoot weight". This causes patient's body fat levels to be greater than before the disorder.{{Cite journal |last1=Dulloo |first1=A. G. |last2=Jacquet |first2=J. |last3=Girardier |first3=L. |date=March 1997 |title=Poststarvation hyperphagia and body fat overshooting in humans: a role for feedback signals from lean and fat tissues |journal=The American Journal of Clinical Nutrition |volume=65 |issue=3 |pages=717–723 |doi=10.1093/ajcn/65.3.717 |issn=0002-9165 |pmid=9062520 |doi-access=free}} This kind of process for hunger normalization varies between patient and could last anywhere from a few months to multiple years.{{cite book |last1=Garfinkel |first1=Paul E. |title=Handbook of Treatment for Eating Disorders |last2=Garner |first2=David M. |date=1997 |publisher=Guilford Press |pages=156–157 |quote=During the weekends in particular, some of the men found it difficult to stop eating. Their daily intake commonly ranged between 8,000 and 10,000 calories. [...] After about 5 months of refeeding, the majority of the men reported some normalization of their eating patterns, but for some the extreme overconsumption persisted. [...] More than 8 months after renourishment began, most men had returned to normal eating patterns; however, a few were still eating abnormal amounts.}}

Treatment professionals tend to be conservative with refeeding in anorexic patients due to the risk of refeeding syndrome (RFS), which occurs when a malnourished person is refed too quickly for their body to be able to adapt. Two of the most common indicators that RFS is occurring are low phosophate levels and low potassium levels.{{cite book |vauthors=Maniscalco J |chapter=Malnutrition: Refeeding Syndrome |veditors=Zaoutis LB, Chiang VW |title=Comprehensive Pediatric Hospital Medicine |date=2007 |pages=633–640 (637–638) |publisher=Elsevier Inc. |isbn=978-0-323-03004-5 |doi=10.1016/B978-032303004-5.50103-4 |chapter-url=https://www.sciencedirect.com/topics/medicine-and-dentistry/refeeding-syndrome |archive-url=https://web.archive.org/web/20240121042053/https://www.sciencedirect.com/topics/medicine-and-dentistry/refeeding-syndrome |archive-date=2024-01-21 |quote=Hypophosphatemia is considered the hallmark of refeeding syndrome, although other imbalances may occur as well, including hypokalemia and hypomagnesemia.}} RFS is most likely to happen in severely or extremely underweight anorexics, as well as when medical comorbidities, such as infection or cardiac failure, are present. In these circumstances, it is recommended to start refeeding more slowly but to build up rapidly as long as RFS does not occur. Recommendations on energy requirements in the most medically compromised patients vary, from 5–10 kcal/kg/day to 1900 kcal/day.{{cite journal |vauthors=O'Connor G, Nicholls D |title=Refeeding hypophosphatemia in adolescents with anorexia nervosa: a systematic review |journal=Nutrition in Clinical Practice |volume=28 |issue=3 |pages=358–364 |date=June 2013 |pmid=23459608 |pmc=4108292 |doi=10.1177/0884533613476892}}{{cite web |url=https://www.nice.org.uk/guidance/cg32/chapter/1-Guidance#what-to-give-in-hospital-and-the-community%20NICE%20guideline%20on%20Nutrition%20support%5D |title=Nutrition support for adults: oral nutrition support, enteral tube feeding and parenteral nutrition |author= |date=4 August 2017 |publisher=NICE |access-date=8 March 2021}} This risk-averse approach can lead to underfeeding, which results in poorer outcomes for short- and long-term recovery.

Pharmaceuticals have limited benefit for anorexia itself.{{cite journal |vauthors=Pinna F, Sanna L, Carpiniello B |title=Alexithymia in eating disorders: therapeutic implications |journal=Psychology Research and Behavior Management |volume=8 |pages=1–15 |year=2015 |pmid=25565909 |pmc=4278740 |doi=10.2147/PRBM.S52656 |doi-access=free}} There is a lack of good information from which to make recommendations concerning the effectiveness of antidepressants in treating anorexia.{{cite journal |vauthors=Claudino AM, Hay P, Lima MS, Bacaltchuk J, Schmidt U, Treasure J |title=Antidepressants for anorexia nervosa |journal=The Cochrane Database of Systematic Reviews |issue=1 |pages=CD004365 |date=January 2006 |pmid=16437485 |doi=10.1002/14651858.CD004365.pub2}} Administration of olanzapine has been shown to result in a modest but statistically significant increase in body weight of anorexia nervosa patients.{{cite journal |vauthors=Meftah AM, Deckler E, Citrome L, Kantrowitz JT |title=New discoveries for an old drug: a review of recent olanzapine research |journal=Postgraduate Medicine |volume=132 |issue=1 |pages=80–90 |date=January 2020 |pmid=31813311 |doi=10.1080/00325481.2019.1701823 |s2cid=208957067}} Other types of medication that can be used to treat Anorexia Nervosa are Prozac and Zyprexa. Prozac is a type of Selective Serotonin Reuptake Inhibitor which can be used to maintain a healthy weight in patients once they reach a healthy weight while Zyprexa is used to calm obsessive thinking and increase weight gain in patients.{{Cite web |last=Staff |first=Eating Disorder Hope |date=2017-04-02 |title=Common Medication Treatments for Anorexia: An Overview |url=https://www.eatingdisorderhope.com/blog/common-medication-treatments-anorexia |access-date=2025-03-06 |website=Eating Disorder Hope |language=en-US}}

Patients with AN may be deemed to have a lack of insight regarding the necessity of treatment, and thus may be involuntarily treated without their consent.{{cite journal |vauthors=Atti AR, Mastellari T, Valente S, Speciani M, Panariello F, De Ronchi D |title=Compulsory treatments in eating disorders: a systematic review and meta-analysis |journal=Eating and Weight Disorders |volume=26 |issue=4 |pages=1037–1048 |date=May 2021 |pmid=33099675 |pmc=8062396 |doi=10.1007/s40519-020-01031-1}}{{Rp|page=1038}} AN has a high mortality and patients admitted in a severely ill state to medical units are at particularly high risk.{{cite journal |vauthors=Arcelus J, Mitchell AJ, Wales J, Nielsen S |title=Mortality rates in patients with anorexia nervosa and other eating disorders. A meta-analysis of 36 studies |journal=Archives of General Psychiatry |volume=68 |issue=7 |pages=724–731 |date=July 2011 |pmid=21727255 |doi=10.1001/archgenpsychiatry.2011.74 |doi-access=free}} Diagnosis can be challenging, risk assessment may not be performed accurately, consent and the need for compulsion may not be assessed appropriately, refeeding syndrome may be missed or poorly treated and the behavioural and family problems in AN may be missed or poorly managed.{{cite journal |vauthors=Robinson P |year=2012 |title=Avoiding deaths in hospital from anorexia nervosa: the MARSIPAN project |journal=The Psychiatrist |volume=36 |issue=3 |pages=109–13 |doi=10.1192/pb.bp.111.036699 |doi-access=free}} Guidelines published by the Royal College of Psychiatrists recommend that medical and psychiatric experts work together in managing severely ill people with AN.{{cite web |author=MARSIPAN Working Group |title = CR189: Management of Really Sick Patients with Anorexia Nervosa |publisher=Royal College of Psychiatrists |date=2014 |url=http://www.rcpsych.ac.uk/usefulresources/publications/collegereports/cr/cr189.aspx |archive-url=https://web.archive.org/web/20160421205628/http://www.rcpsych.ac.uk/usefulresources/publications/collegereports/cr/cr189.aspx |archive-date=21 April 2016 |edition=Second |page=6}}

Patients involved in treatment sometimes felt that treatment focused on biological aspects of body weight and eating behaviour change rather than their perceptions or emotional state.{{cite journal |vauthors=Conti JE, Joyce C, Hay P, Meade T |title="Finding my own identity": a qualitative metasynthesis of adult anorexia nervosa treatment experiences |journal=BMC Psychology |volume=8 |issue=1 |pages=110 |date=October 2020 |pmid=33092638 |pmc=7583290 |doi=10.1186/s40359-020-00476-4 |doi-access=free}}{{Rp|page=8}} Patients felt that a therapists trust in them shown by being treated as a complete person with their own capacities was significant.{{Rp|page=9}} Some patients defined recovery from AN in terms of reclaiming a lost identity.{{Rp|page=10}} Additionally, access to timely treatment can be hindered by systemic challenges within the medical system. Some individuals have reported experiencing delays in treatment, particularly when transitioning from adolescence to adulthood.doi: 10.1192/bjo.2018.78

Healthcare workers involved in the treatment of anorexia reported frustration and anger to setbacks in treatment and noncompliance and were afraid of patients dying. Some healthcare workers felt that they did not understand the treatment and that medical doctors were making decisions.{{cite journal |vauthors=Graham MR, Tierney S, Chisholm A, Fox JR |title=The lived experience of working with people with eating disorders: A meta-ethnography |journal=The International Journal of Eating Disorders |volume=53 |issue=3 |pages=422–441 |date=March 2020 |pmid=31904870 |doi=10.1002/eat.23215 |s2cid=209894802 |url=https://orca.cardiff.ac.uk/id/eprint/127249/1/Fox.%20The%20lived%20experience.pdf}}{{Rp|page=11}} They may feel powerless to improve a patient's situation and deskilled as a result.{{Rp|page=12}} Healthcare workers involved in monitoring patients consumption of food felt watched themselves.{{Rp|page=12}} Healthcare workers often feel a degree of moral dissonance of not being in control of outcomes which they may protect against by focusing on individual tasks, avoiding identifying with patients (for example by making their eating behavior very different and not sharing personal information with patients), and blaming patients for their distress.{{Rp|page=13,14}} Healthcare workers would inflexibly follow process to avoid responsibility.{{Rp|page=13}} Healthcare workers attempted to reach balance by gradually giving patients back control avoiding feeling sole responsibility for outcomes, being mindful of their emotional state, and trying to view eating disorders as external from patients.{{Rp|page=13}}

File:Eating disorders world map-Deaths per million persons-WHO2012.svg

AN has the highest mortality rate of any psychological disorder.{{cite journal |vauthors=Espie J, Eisler I |title=Focus on anorexia nervosa: modern psychological treatment and guidelines for the adolescent patient |journal=Adolescent Health, Medicine and Therapeutics |volume=6 |pages=9–16 |year=2015 |pmid=25678834 |pmc=4316908 |doi=10.2147/AHMT.S70300 |doi-access=free}} The mortality rate is 11 to 12 times greater than in the general population, and the suicide risk is 56 times higher. Half of women with AN achieve a full recovery, while an additional 20–30% may partially recover. Not all people with anorexia recover completely: about 20% develop anorexia nervosa as a chronic disorder. If anorexia nervosa is not treated, serious complications such as heart conditions and kidney failure can arise and eventually lead to death.{{cite journal |vauthors=Bouquegneau A, Dubois BE, Krzesinski JM, Delanaye P |title=Anorexia nervosa and the kidney |journal=American Journal of Kidney Diseases |volume=60 |issue=2 |pages=299–307 |date=August 2012 |pmid=22609034 |doi=10.1053/j.ajkd.2012.03.019}} The average number of years from onset to remission of AN is seven for women and three for men. After ten to fifteen years, 70% of people no longer meet the diagnostic criteria, but many still continue to have eating-related problems.{{cite book |vauthors=Nolen-Hoeksema S |title=Abnormal Psychology |date=2014 |publisher=McGraw Hill Education |isbn=978-0-07-803538-8 |page=342 |edition=Sixth |chapter=Eating Disorders |location=New York}} People who have autism recover more slowly, probably due to autism's effects on thinking patterns, such as reduced cognitive flexibility.{{Cite journal |last1=Saure |first1=Emma |last2=Laasonen |first2=Marja |last3=Lepistö-Paisley |first3=Tuulia |last4=Mikkola |first4=Katri |last5=Ålgars |first5=Monica |last6=Raevuori |first6=Anu |date=July 2020 |title=Characteristics of autism spectrum disorders are associated with longer duration of anorexia nervosa: A systematic review and meta-analysis |journal=The International Journal of Eating Disorders |volume=53 |issue=7 |pages=1056–1079 |doi=10.1002/eat.23259 |issn=1098-108X |pmid=32181530}}

Alexithymia (inability to identify and describe one's own emotions) influences treatment outcome. Recovery is also viewed on a spectrum rather than black and white. According to the Morgan-Russell criteria, individuals can have a good, intermediate, or poor outcome. Even when a person is classified as having a "good" outcome, weight only has to be within 15% of average, and normal menstruation must be present in females. The good outcome also excludes psychological health. Recovery for people with anorexia nervosa is undeniably positive, but recovery does not mean a return to normal.{{cite web |url=https://www.ucsf.edu/news/2019/11/416006/many-patients-anorexia-nervosa-get-better-complete-recovery-elusive-most |title=Many Patients with Anorexia Nervosa Get Better, But Complete Recovery Elusive to Most |vauthors=Leigh S |publisher=The Regents of The University of California |date=November 19, 2019 |website=University of California San Francisco |access-date=June 23, 2021}}

Anorexia nervosa can have serious implications if its duration and severity are significant and if onset occurs before the completion of growth, pubertal maturation, or the attainment of peak bone mass.{{cite journal |vauthors=Donaldson AA, Gordon CM |title=Skeletal complications of eating disorders |journal=Metabolism |volume=64 |issue=9 |pages=943–951 |date=September 2015 |pmid=26166318 |pmc=4546560 |doi=10.1016/j.metabol.2015.06.007 |publisher=Metabolism: Clinical and Experimental}}{{medical citation needed|date=March 2015}} Complications specific to adolescents and children with anorexia nervosa can include growth retardation, as height gain may slow and can stop completely with severe weight loss or chronic malnutrition. In such cases, provided that growth potential is preserved, height increase can resume and reach full potential after normal intake is resumed.{{cite journal |vauthors=Downey AE, Richards A, Tanner AB |title=Linear growth in young people with restrictive eating disorders: "Inching" toward consensus |journal=Frontiers in Psychiatry |volume=14 |pages=1094222 |date=2023-03-03 |pmid=36937727 |pmc=10020618 |doi=10.3389/fpsyt.2023.1094222 |doi-access=free}} Height potential is normally preserved if the duration and severity of illness are not significant or if the illness is accompanied by delayed bone age (especially prior to a bone age of approximately 15 years), as hypogonadism may partially counteract the effects of undernutrition on height by allowing for a longer duration of growth compared to controls.{{medical citation needed|date=March 2015}} Appropriate early treatment can preserve height potential, and may even help to increase it in some post-anorexic subjects, due to factors such as long-term reduced estrogen-producing adipose tissue levels compared to premorbid levels.{{medical citation needed|date=March 2015}} In some cases, especially where onset is before puberty, complications such as stunted growth and pubertal delay are usually reversible.{{cite journal |journal=National Collaborating Centre for Mental Health |year=2004 |title=Core interventions in the treatment and management of anorexia nervosa, bulimia nervosa and related eating disorders |url=http://www.nice.org.uk/nicemedia/pdf/CG9FullGuideline.pdf |url-status=live |archive-url=https://web.archive.org/web/20140327055429/http://www.nice.org.uk/nicemedia/pdf/CG9FullGuideline.pdf |archive-date=27 March 2014}}

Anorexia nervosa causes alterations in the female reproductive system; significant weight loss, as well as psychological stress and intense exercise, typically results in a cessation of menstruation in women who are past puberty. In patients with anorexia nervosa, there is a reduction of the secretion of gonadotropin releasing hormone in the central nervous system which prevents ovulation.{{cite journal |vauthors=Vyver E, Steinegger C, Katzman DK |title=Eating disorders and menstrual dysfunction in adolescents |journal=Annals of the New York Academy of Sciences |volume=1135 |issue=1 |pages=253–264 |year=2008 |pmid=18574232 |doi=10.1196/annals.1429.013 |s2cid=42042720 |bibcode=2008NYASA1135..253V}} Anorexia nervosa can also result in pubertal delay or arrest. Both height gain and pubertal development are dependent on the release of growth hormone and gonadotropins (LH and FSH) from the pituitary gland. Suppression of gonadotropins in people with anorexia nervosa has been documented.{{cite journal |vauthors=Devlin MJ, Walsh BT, Katz JL, Roose SP, Linkie DM, Wright L, Vande Wiele R, Glassman AH |title=Hypothalamic-pituitary-gonadal function in anorexia nervosa and bulimia |journal=Psychiatry Research |volume=28 |issue=1 |pages=11–24 |date=April 1989 |pmid=2500676 |doi=10.1016/0165-1781(89)90193-5 |s2cid=39940665}} Typically, growth hormone (GH) levels are high, but levels of IGF-1, the downstream hormone that should be released in response to GH are low; this indicates a state of "resistance" to GH due to chronic starvation. IGF-1 is necessary for bone formation, and decreased levels in anorexia nervosa contribute to a loss of bone density and potentially contribute to osteopenia or osteoporosis.{{cite journal |vauthors=Støving RK, Chen JW, Glintborg D, Brixen K, Flyvbjerg A, Hørder K, Frystyk J |title=Bioactive insulin-like growth factor (IGF) I and IGF-binding protein-1 in anorexia nervosa |journal=The Journal of Clinical Endocrinology and Metabolism |volume=92 |issue=6 |pages=2323–2329 |date=June 2007 |pmid=17389700 |doi=10.1210/jc.2006-1926 |doi-access=free}} Anorexia nervosa can also result in reduction of peak bone mass. Buildup of bone is greatest during adolescence, and if onset of anorexia nervosa occurs during this time and stalls puberty, low bone mass may be permanent.{{cite journal |vauthors=Misra M, Klibanski A |title=Anorexia nervosa and bone |journal=Journal of Endocrinology |volume=221 |issue=3 |pages=R163–R176 |date = June 2014 |pmid=24898127 |pmc=4047520 |doi=10.1530/JOE-14-0039 |df=dmy-all}}

Hepatic steatosis, or fatty infiltration of the liver, can also occur, and is an indicator of malnutrition in children.{{Cite book |title=Walker's Pediatric Gastrointestinal Disease |url=https://books.google.com/books?id=bG3nVUqIbegC&q=hepatic%20steatosis%20malnutrition%20children&pg=PA1105 |publisher=PMPH-USA |date=1 April 2008 |access-date=9 April 2015 |isbn=978-1-55009-364-3 |vauthors=Kleinman R}} Neurological disorders that may occur as complications include seizures and tremors. Wernicke encephalopathy, which results from vitamin B1 deficiency, has been reported in patients who are extremely malnourished; symptoms include confusion, problems with the muscles responsible for eye movements and abnormalities in walking gait.{{Citation needed|date=February 2025}}

The most common gastrointestinal complications of anorexia nervosa are delayed stomach emptying and constipation, but also include elevated liver function tests, diarrhea, acute pancreatitis, gastroesophageal reflux disease (GERD), difficulty swallowing, and, rarely, superior mesenteric artery syndrome.{{cite journal |vauthors=Norris ML, Harrison ME, Isserlin L, Robinson A, Feder S, Sampson M |title=Gastrointestinal complications associated with anorexia nervosa: A systematic review |journal=The International Journal of Eating Disorders |volume=49 |issue=3 |pages=216–237 |date=March 2016 |pmid=26407541 |doi=10.1002/eat.22462}} Acid exposure from GERD and self-induced vomiting can cause dental problems, such as tooth enamel erosion and gum disease.{{cite web |last1=Gibson |first1=Dennis |title=The Effects of Purging on Oral Health |url=https://www.acute.org/blog/effects-purging-oral-health |website=ACUTE Center for Eating Disorders & Severe Malnutrition |access-date=2025-02-12 |date=2024-12-12}}{{cite web |title=FACT SHEET: Eating Disorders |url=https://cdho.org/factsheets/eating-disorders/ |website=College of Dental Hygienists of Ontario |access-date=12 February 2025 |archive-url=https://web.archive.org/web/20250213013535/https://cdho.org/factsheets/eating-disorders/ |archive-date=13 February 2025 |url-status=live}} Delayed stomach emptying, or gastroparesis, often develops following food restriction and weight loss; the most common symptom is bloating with gas and abdominal distension, and often occurs after eating. Other symptoms of gastroparesis include early satiety, fullness, nausea, and vomiting. The symptoms may inhibit efforts at eating and recovery, but can be managed by limiting high-fiber foods, using liquid nutritional supplements, or using metoclopramide to increase emptying of food from the stomach. Gastroparesis generally resolves when weight is regained.{{Citation needed|date=February 2025}}

Anorexia nervosa increases the risk of sudden cardiac death, though the precise cause is unknown. Cardiac complications include structural and functional changes to the heart.{{cite journal |vauthors=Sachs KV, Harnke B, Mehler PS, Krantz MJ |title=Cardiovascular complications of anorexia nervosa: A systematic review |journal=The International Journal of Eating Disorders |volume=49 |issue=3 |pages=238–248 |date=March 2016 |pmid=26710932 |doi=10.1002/eat.22481}} Some of these cardiovascular changes are mild and are reversible with treatment, while others may be life-threatening. Cardiac complications can include arrhythmias, abnormally slow heart beat, low blood pressure, decreased size of the heart muscle, reduced heart volume, mitral valve prolapse, myocardial fibrosis, and pericardial effusion.

Abnormalities in conduction and repolarization of the heart that can result from anorexia nervosa include QT prolongation, increased QT dispersion, conduction delays, and junctional escape rhythms. Electrolyte abnormalities, particularly hypokalemia and hypomagnesemia, can cause anomalies in the electrical activity of the heart, and result in life-threatening arrhythmias. Hypokalemia most commonly results in patients with anorexia when restricting is accompanied by purging (induced vomiting or laxative use). Hypotension (low blood pressure) is common, and symptoms include fatigue and weakness. Orthostatic hypotension, a marked decrease in blood pressure when standing from a supine position, may also occur. Symptoms include lightheadedness upon standing, weakness, and cognitive impairment, and may result in fainting or near-fainting. Orthostasis in anorexia nervosa indicates worsening cardiac function and may indicate a need for hospitalization. Hypotension and orthostasis generally resolve upon recovery to a normal weight. The weight loss in anorexia nervosa also causes atrophy of cardiac muscle. This leads to decreased ability to pump blood, a reduction in the ability to sustain exercise, a diminished ability to increase blood pressure in response to exercise, and a subjective feeling of fatigue.

Some individuals may also have a decrease in cardiac contractility. Cardiac complications can be life-threatening, but the heart muscle generally improves with weight gain, and the heart normalizes in size over weeks to months, with recovery.{{cite journal |vauthors=Goldberg SJ, Comerci GD, Feldman L |title=Cardiac output and regional myocardial contraction in anorexia nervosa |journal=Journal of Adolescent Health Care |volume=9 |issue=1 |pages=15–21 |date=January 1988 |pmid=3335466 |doi=10.1016/0197-0070(88)90013-7}} Atrophy of the heart muscle is a marker of the severity of the disease, and while it is reversible with treatment and refeeding, it is possible that it may cause permanent, microscopic changes to the heart muscle that increase the risk of sudden cardiac death. Individuals with anorexia nervosa may experience chest pain or palpitations; these can be a result of mitral valve prolapse. Mitral valve prolapse occurs because the size of the heart muscle decreases while the tissue of the mitral valve remains the same size. Studies have shown rates of mitral valve prolapse of around 20 percent in those with anorexia nervosa, while the rate in the general population is estimated at 2–4 percent.{{cite journal |vauthors=Johnson GL, Humphries LL, Shirley PB, Mazzoleni A, Noonan JA |title=Mitral valve prolapse in patients with anorexia nervosa and bulimia |journal=Archives of Internal Medicine |volume=146 |issue=8 |pages=1525–1529 |date=August 1986 |pmid=3460535 |doi=10.1001/archinte.1986.00360200083014}} It has been suggested that there is an association between mitral valve prolapse and sudden cardiac death, but it has not been proven to be causative, either in patients with anorexia nervosa or in the general population.

Rates of relapse after treatment range 30–72% over a period of 2–26 months, with a rate of approximately 50% in 12 months after weight restoration.{{cite journal |vauthors=Frostad S, Rozakou-Soumalia N, Dârvariu Ş, Foruzesh B, Azkia H, Larsen MP, Rowshandel E, Sjögren JM |title=BMI at Discharge from Treatment Predicts Relapse in Anorexia Nervosa: A Systematic Scoping Review |journal=Journal of Personalized Medicine |volume=12 |issue=5 |pages=836 |date=May 2022 |pmid=35629258 |pmc=9144864 |doi=10.3390/jpm12050836 |doi-access=free}} Relapse occurs in approximately a third of people in hospital, and is greatest in the first six to eighteen months after release from an institution.{{cite journal |vauthors=Hasan TF, Hasan H |title=Anorexia nervosa: a unified neurological perspective |journal=International Journal of Medical Sciences |volume=8 |issue=8 |pages=679–703 |year=2011 |pmid=22135615 |pmc=3204438 |doi=10.7150/ijms.8.679}} BMI or measures of body fat and leptin levels at discharge were the strongest predictors of relapse, as well as signs of eating psychopathology at discharge. Duration of illness, age, severity, the proportion of AN binge-purge subtype, and presence of comorbidities are also contributing factors.{{Citation needed|date=February 2025}}

{{Expand section|with=possible reasons for the higher prevalence in women|date=December 2024}}

Anorexia is estimated to occur in 0.9% to 4.3% of women and 0.2% to 0.3% of men in Western countries at some point in their life. About 0.4% of young females are affected in a given year and it is estimated to occur three to ten times less commonly in males.{{cite journal |vauthors=Striegel-Moore RH, Rosselli F, Perrin N, DeBar L, Wilson GT, May A, Kraemer HC |title=Gender difference in the prevalence of eating disorder symptoms |journal=The International Journal of Eating Disorders |volume=42 |issue=5 |pages=471–474 |date=July 2009 |pmid=19107833 |pmc=2696560 |doi=10.1002/eat.20625}} The cause of this disparity is not well-established but is thought to be linked to both biological and socio-cultural factors.{{Cite journal |last1=Tarchi |first1=Livio |last2=Stanghellini |first2=Giovanni |last3=Ricca |first3=Valdo |last4=Castellini |first4=Giovanni |date=2024-01-13 |title=The primacy of ocular perception: a narrative review on the role of gender identity in eating disorders |journal=Eating and Weight Disorders - Studies on Anorexia, Bulimia and Obesity |language=en |volume=29 |issue=1 |pages=8 |doi=10.1007/s40519-023-01632-6 |issn=1590-1262 |pmc=10787908 |pmid=38217553}} Rates in most of the developing world are unclear. Often it begins during the teen years or young adulthood. Medical students are a high risk group, with an overall estimated prevalence of 10.4% globally.{{cite journal |vauthors=Jahrami H, Sater M, Abdulla A, Faris MA, AlAnsari A |title=Eating disorders risk among medical students: a global systematic review and meta-analysis |journal=Eating and Weight Disorders |volume=24 |issue=3 |pages=397–410 |date=June 2019 |pmid=29785631 |doi=10.1007/s40519-018-0516-z |s2cid=29156560}}

The lifetime rate of atypical anorexia nervosa, a form of ED-NOS in which the person loses a significant amount of weight and is at risk for serious medical complications despite having a higher body-mass index, is much higher, at 5–12%.{{cite book |vauthors=Zanetti T |chapter=Epidemiology of Eating Disorders |title=Eating Disorders and the Skin |year=2013 |pages=9–15 |doi=10.1007/978-3-642-29136-4_2 |isbn=978-3-642-29135-7}} Additionally, a UCSF study showed severity of illness is independent of current BMI, and "patients with large, rapid, or long-duration of weight loss were more severely ill regardless of their current weight."{{cite journal |vauthors=Garber AK, Cheng J, Accurso EC, Adams SH, Buckelew SM, Kapphahn CJ, Kreiter A, Le Grange D, Machen VI, Moscicki AB, Saffran K, Sy AF, Wilson L, Golden NH |title=Weight Loss and Illness Severity in Adolescents With Atypical Anorexia Nervosa |journal=Pediatrics |volume=144 |issue=6 |date=December 2019 |pmid=31694978 |pmc=6889949 |doi=10.1542/peds.2019-2339}}

While anorexia became more commonly diagnosed during the 20th century it is unclear if this was due to an increase in its frequency or simply better diagnosis. Most studies show that since at least 1970 the incidence of AN in adult women is fairly constant, while there is some indication that the incidence may have been increasing for girls aged between 14 and 20.

In non-Westernized countries, including those in Africa (excluding South Africa), eating disorders are less frequently reported and studied compared to Western countries,{{cite journal |vauthors=Makino M, Tsuboi K, Dennerstein L |title=Prevalence of eating disorders: a comparison of Western and non-Western countries |journal=MedGenMed |volume=6 |issue=3 |pages=49 |date=September 2004 |pmid=15520673 |pmc=1435625}} with available data mostly limited to case reports and isolated studies rather than prevalence investigations. Theories to explain these lower rates of eating disorders, lower reporting, and lower research rates in these countries include the attention to effects of westernisation and culture change on the prevalence of anorexia.{{cite journal |vauthors=Tsai G |title=Eating disorders in the Far East |journal=Eating and Weight Disorders |volume=5 |issue=4 |pages=183–197 |date=December 2000 |pmid=11216126 |doi=10.1007/BF03354445 |s2cid=41396054}}{{clarify|date=June 2024}}

Athletes are often overlooked as anorexic.{{cite journal |vauthors=Bonci CM, Bonci LJ, Granger LR, Johnson CL, Malina RM, Milne LW, Ryan RR, Vanderbunt EM |year=2008 |title=National athletic trainers' association position statement: preventing, detecting, and managing disordered eating in athletes |journal=Journal of Athletic Training |volume=43 |issue=1 |pages=80–108 |doi=10.4085/1062-6050-43.1.80 |pmc=2231403 |pmid=18335017}} Research emphasizes the importance to take athletes' diet, weight and symptoms into account when diagnosing anorexia, instead of just looking at weight and BMI. For athletes, ritualized activities such as weigh-ins place emphasis on gaining and losing large amounts of weight, which may promote the development of eating disorders among them.{{cite journal |vauthors=Thiel A, Gottfried H, Hesse FW |date=October 1993 |title=Subclinical eating disorders in male athletes. A study of the low weight category in rowers and wrestlers |journal=Acta Psychiatrica Scandinavica |volume=88 |issue=4 |pages=259–265 |doi=10.1111/j.1600-0447.1993.tb03454.x |pmid=8256643 |s2cid=10232724}} Furthermore, the competitive mindset of elite athletes makes them especially vulnerable to anorexia nervosa. The disorder is often largely rooted in a desire to maintain control over one’s own life. The highly competitive mindset that athletic pursuits can easily translate to the world of disordered eating. Eating becomes “like a game” or “challenge”, where the athlete is completely focused on “winning the game”; one elite swimmer with severe anorexia nervosa recalls that “it was always about losing more” and she “never wanted the game to be over”.{{Cite journal |last1=Hughes |first1=Colleen S. |last2=Hughes |first2=Suzanne |date=July–August 2004 |title=The Female Athlete Syndrome: Anorexia Nervosa—Reflections on a Personal Journey |url=https://journals.lww.com/orthopaedicnursing/abstract/2004/07000/the_female_athlete_syndrome__anorexia.10.aspx |journal=Orthopaedic Nursing |language=en-US |volume=23 |issue=4 |pages=252–260 |doi=10.1097/00006416-200407000-00010 |pmid=15379177 |issn=0744-6020}}

While anorexia nervosa is more commonly found in women, it can also affect men, with a lifetime prevalence of 0.3% in men.{{Cite web |date=2022-05-20 |title=Male Anorexia: Understanding Eating Disorders in Men and Boys |url=https://psychcentral.com/eating-disorders/male-anorexia |access-date=2024-02-29 |website=Psych Central |language=en}} However, a lack of awareness of eating disorders in males may lead to underdiagnosis and underreporting. This can include a lack of knowledge about what kinds of behaviors males with eating disorders might display, as they differ slightly from those found in females, with a 2009 survey showing that females are more inclined to report fasting, body checking, and body avoidance, whereas males are more prone to report overeating. Due to this limited knowledge of how anorexia nervosa is presented in males, it often takes men longer to be diagnosed and receive treatment than women.{{Cite journal |last1=Redondo |first1=M. D. M. Lázaro |last2=Brasas |first2=F. De la Torre |last3=Domínguez |first3=A. Duque |last4=Hernández |first4=N. Echeverría |last5=Díaz |first5=L. Martín |last6=Montero |first6=C. García |last7=Navarro |first7=M. Otálora |last8=Villaseñor |first8=A. Mas |last9=Suárez |first9=J. I. Bango |date=2016 |title=Anorexia Nervosa And Dissociative Disorders In Males: a Case Report |url=https://www.cambridge.org/core/journals/european-psychiatry/article/anorexia-nervosa-and-dissociative-disorders-in-males-a-case-report/3B4A5FB40A95BA160A9298CB1A815A11 |journal=European Psychiatry |language=en |volume=33 |issue=S1 |pages=S430 |doi=10.1016/j.eurpsy.2016.01.1556 |issn=0924-9338}} An additional difference is in the use of supplements to affect bodyweight, with women being more prone to using diet pills and men being more prone to using anabolic steroids.

Moreover, men who exhibit symptoms of anorexia may not meet the BMI criteria outlined in the DSM-IV due to having more muscle mass and therefore a higher bodyweight. Consequently, a subclinical diagnosis, such as Eating Disorder Not Otherwise Specified (ED-NOS) in the DSM-IV or Other Specified Feeding or Eating Disorder (OSFED) in the DSM-5, is often made instead.{{cite journal |vauthors=Thomas JJ, Vartanian LR, Brownell KD |date=May 2009 |title=The relationship between eating disorder not otherwise specified (EDNOS) and officially recognized eating disorders: meta-analysis and implications for DSM |journal=Psychological Bulletin |volume=135 |issue=3 |pages=407–433 |doi=10.1037/a0015326 |pmc=2847852 |pmid=19379023}}

Men with anorexia may also experience body dysmorphia, reporting their bodies to be twice as large than in actuality, and body dissatisfaction, especially with regard to muscularity and body composition. Men tend to place more emphasis on a muscular build as opposed to pursuing thinness.{{Cite journal |last1=Timko |first1=C. Alix |last2=DeFilipp |first2=Levi |last3=Dakanalis |first3=Antonios |date=2019-01-12 |title=Sex Differences in Adolescent Anorexia and Bulimia Nervosa: Beyond the Signs and Symptoms |journal=Current Psychiatry Reports |language=en |volume=21 |issue=1 |pages=1 |doi=10.1007/s11920-019-0988-1 |pmid=30637488 |pmc=6559358 |issn=1535-1645}} As in the case of women, men are more prone to develop an eating disorder if their occupation or sport emphasizes having a slim physique or lighter weight, like modeling, dancing, horse racing, wrestling, and gymnastics. Hormonal changes may also be observed in males with anorexia nervosa, with marked changes in their serum testosterone, luteinizing hormone, and follicle stimulating hormone. Such extreme endocrine disturbances can potentially result in infertility.{{Cite journal |last=Wooldridge |first=Tom |date=September 17, 2012 |title=An Overview of Anorexia Nervosa in Males |journal=Eating Disorders: The Journal of Treatment and Prevention |volume=20 |issue=5 |pages=368–378|doi=10.1080/10640266.2012.715515 |pmid=22985234}}

Anorexic men are sometimes colloquially referred to as manorexic{{Cite book |url=https://books.google.com/books?id=m1_6qjqNey8C&q=anorexia%20manorexia&pg=PA69 |title=Hope with Eating Disorders |vauthors=Crilly L |date=2 April 2012 |publisher=Hay House, Inc |isbn=978-1-84850-906-1 |access-date=9 April 2015}} or as having bigorexia.

An increasing trend of anorexia among the elderly, termed "Anorexia of Aging,"{{cite journal |vauthors=Landi F, Calvani R, Tosato M, Martone AM, Ortolani E, Savera G, Sisto A, Marzetti E |title=Anorexia of Aging: Risk Factors, Consequences, and Potential Treatments |journal=Nutrients |volume=8 |issue=2 |pages=69 |date=January 2016 |pmid=26828516 |pmc=4772033 |doi=10.3390/nu8020069 |doi-access=free}} is observed, characterized by behaviors similar to those seen in typical anorexia nervosa but often accompanied by excessive laxative use. Most geriatric anorexia patients limit their food intake to dairy or grains, whereas an adolescent anorexic has a more general limitation.

This eating disorder that affects older adults has two types – early onset and late onset. Early onset refers to a recurrence of anorexia in late life in an individual who experienced the disease during their youth. Late onset describes instances where the eating disorder begins for the first time late in life.

The stimulus for anorexia in elderly patients is typically a loss of control over their lives, which can be brought on by many events, including moving into an assisted living facility.{{Cite web |vauthors=Ekern B |date=2016-02-25 |title=Common Types of Eating Disorders Observed in the Elderly Population |url=https://www.eatingdisorderhope.com/blog/eating-disorders-observed-elderly |access-date=12 June 2022 |website=Eating Disorder Hope |language=en-US}} This is also a time when most older individuals experience a rise in conflict with family members, such as limitations on driving or limitations on personal freedom, which increases the likelihood of an issue with anorexia. There can be physical issues in the elderly that leads to anorexia of aging, including a decline in chewing ability, a decline in taste and smell, and a decrease in appetite.{{cite journal |vauthors=Donini LM, Poggiogalle E, Piredda M, Pinto A, Barbagallo M, Cucinotta D, Sergi G |title=Anorexia and eating patterns in the elderly |journal=PLOS ONE |volume=8 |issue=5 |pages=e63539 |date=2 May 2013 |pmid=23658838 |pmc=3642105 |doi=10.1371/journal.pone.0063539 |bibcode=2013PLoSO...863539D |doi-access=free}} Psychological reasons for the elderly to develop anorexia can include depression and bereavement, and even an indirect attempt at suicide. There are also common comorbid psychiatric conditions with aging anorexics, including major depression, anxiety disorder, obsessive compulsive disorder, bipolar disorder, schizophrenia, and dementia.{{cite journal |vauthors=Lapid MI, Prom MC, Burton MC, McAlpine DE, Sutor B, Rummans TA |title=Eating disorders in the elderly |journal=International Psychogeriatrics |volume=22 |issue=4 |pages=523–536 |date=June 2010 |pmid=20170590 |doi=10.1017/S1041610210000104 |s2cid=38114971 |doi-access=free}}

The signs and symptoms that go along with anorexia of aging are similar to what is observed in adolescent anorexia, including sudden weight loss, unexplained hair loss or dental problems, and a desire to eat alone.

There are also several medical conditions that can result from anorexia in the elderly. An increased risk of illness and death can be a result of anorexia. There is also a decline in muscle and bone mass as a result of a reduction in protein intake during anorexia. Another result of anorexia in the aging population is irreparable damage to kidneys, heart or colon and an imbalance of electrolytes.{{cite journal |vauthors=Morley JE, Silver AJ |title=Anorexia in the elderly |journal=Neurobiology of Aging |volume=9 |issue=1 |pages=9–16 |date=1 January 1988 |pmid=2898107 |doi=10.1016/S0197-4580(88)80004-6 |s2cid=3099767}}

Many assessments are available to diagnose anorexia in the aging community. These assessments include the Simplified Nutritional Assessment Questionnaire (SNAQ){{cite journal |vauthors=Lau S, Pek K, Chew J, Lim JP, Ismail NH, Ding YY, Cesari M, Lim WS |title=The Simplified Nutritional Appetite Questionnaire (SNAQ) as a Screening Tool for Risk of Malnutrition: Optimal Cutoff, Factor Structure, and Validation in Healthy Community-Dwelling Older Adults |journal=Nutrients |volume=12 |issue=9 |date=September 2020 |page=2885 |pmid=32967354 |pmc=7551805 |doi=10.3390/nu12092885 |doi-access=free}} and Functional Assessment of Anorexia/Cachexia Therapy (FAACT).{{cite web |title=Functional Assessment of Anorexia/Cachexia Treatment (FAACT) |url=https://www.facit.org/measures/FAACT |work=FACIT.org |archive-url= |archive-date=}} Specific to the geriatric populace, the interRAI system{{cite journal |vauthors=Devriendt E, Wellens NI, Flamaing J, Declercq A, Moons P, Boonen S, Milisen K |title=The interRAI Acute Care instrument incorporated in an eHealth system for standardized and web-based geriatric assessment: strengths, weaknesses, opportunities and threats in the acute hospital setting |journal=BMC Geriatrics |volume=13 |issue= |pages=90 |date=September 2013 |pmid=24007312 |pmc=3766642 |doi=10.1186/1471-2318-13-90 |doi-access=free}} identifies detrimental conditions in assisted living facilities and nursing homes. Even a simple screening for nutritional insufficiencies such as low levels of important vitamins, can help to identify someone who has anorexia of aging.

Anorexia in the elderly should be identified by the retirement communities but is often overlooked, especially in patients with dementia. Some studies report that malnutrition is prevalent in nursing homes, with up to 58% of residents suffering from it, which can lead to the difficulty of identifying anorexia. One of the challenges with assisted living facilities is that they often serve bland, monotonous food, which lessens residents' desire to eat.

The treatment for anorexia of aging is undifferentiated as anorexia for any other age group. Some of the treatment options include outpatient and inpatient facilities, antidepressant medication and behavioral therapy such as meal observation and discussing eating habits.

{{Main|History of anorexia nervosa}}

File:Anorexia case-1900-Nouvelle icononographie de la Salpetriere.jpg

The history of anorexia nervosa begins with descriptions of religious fasting dating from the Hellenistic era{{cite journal |vauthors=Pearce JM |title=Richard Morton: origins of anorexia nervosa |journal=European Neurology |volume=52 |issue=4 |pages=191–192 |year=2004 |pmid=15539770 |doi=10.1159/000082033 |s2cid=30482453}} and continuing into the medieval period. The medieval practice of self-starvation by women, including some young women, in the name of religious piety and purity also concerns anorexia nervosa; it is sometimes referred to as anorexia mirabilis.{{cite journal |vauthors=Espi Forcen F |title=Anorexia mirabilis: the practice of fasting by Saint Catherine of Siena in the late Middle Ages |journal=The American Journal of Psychiatry |volume=170 |issue=4 |pages=370–371 |date=April 2013 |pmid=23545792 |doi=10.1176/appi.ajp.2012.12111457}}{{cite journal |vauthors=Harris JC |title=Anorexia nervosa and anorexia mirabilis: Miss K. R--and St Catherine Of Siena |journal=JAMA Psychiatry |volume=71 |issue=11 |pages=1212–1213 |date=November 2014 |pmid=25372187 |doi=10.1001/jamapsychiatry.2013.2765}} The earliest medical descriptions of anorexic illnesses are generally credited to English physician Richard Morton in 1689.

Etymologically, anorexia is a term of Greek origin: an- (ἀν-, prefix denoting negation) and orexis (ὄρεξις, "appetite"), translating literally to "a loss of appetite". In and of itself, this term does not have a harmful connotation, e.g., exercise-induced anorexia simply means that hunger is naturally suppressed during and after sufficiently intense exercise sessions.{{cite journal |vauthors=King NA, Burley VJ, Blundell JE |title=Exercise-induced suppression of appetite: effects on food intake and implications for energy balance |journal=European Journal of Clinical Nutrition |volume=48 |issue=10 |pages=715–724 |date=October 1994 |pmid=7835326 |publisher=United States government |quote=Subjective feelings of hunger were significantly suppressed during and after intense exercise sessions (P 0.01), but the suppression was short-lived.}} It is the adjective nervosa that indicates the functional and non-organic nature of the disorder, but this adjective is also often omitted when the context is clear. Despite the literal translation of anorexia, the feeling of hunger in anorexia nervosa is frequently present and the pathological control of this instinct is a source of satisfaction for the patients.{{cite journal |vauthors=Grant JE, Phillips KA |title=Is anorexia nervosa a subtype of body dysmorphic disorder? Probably not, but read on |journal=Harvard Review of Psychiatry |volume=12 |issue=2 |pages=123–126 |date=2004 |pmid=15204807 |pmc=1622894 |doi=10.1080/10673220490447236}}

The term "anorexia nervosa" was coined in 1873 by Sir William Gull, one of Queen Victoria's personal physicians.{{cite journal |vauthors=Gull WW |title=Anorexia nervosa (apepsia hysterica, anorexia hysterica). 1868 |journal=Obesity Research |volume=5 |issue=5 |pages= 498–502 |date=September 1997 |pmid=9385628 |doi=10.1002/j.1550-8528.1997.tb00677.x |doi-access=free}} Gull published a seminal paper providing a number of detailed case descriptions of patients with anorexia nervosa.{{cite book |title=Medical Papers |vauthors=Gull WW |year=1894 |veditors=Acland TD |page=309}} In the same year, French physician Ernest-Charles Lasègue similarly published details of a number of cases in a paper entitled De l'Anorexie hystérique.{{cite news |date=6 September 1873 |title=On Hysterical Anorexia |publisher=Medical Times and Gazette |vauthors=Lasègue E}} See also {{cite journal |vauthors= |title=On hysterical anorexia (a). 1873 |journal=Obesity Research |volume=5 |issue=5 |pages=492–497 |date=September 1997 |pmid=9385627 |doi=10.1002/j.1550-8528.1997.tb00676.x |doi-access=free}}

In the late 19th century anorexia nervosa became widely accepted by the medical profession as a recognized condition. Awareness of the condition was largely limited to the medical profession until the latter part of the 20th century, when German-American psychoanalyst Hilde Bruch published The Golden Cage: the Enigma of Anorexia Nervosa in 1978. Despite major advances in neuroscience,{{cite book |title=Decoding Anorexia: How Breakthroughs in Science Offer Hope for Eating Disorders |vauthors=Arnold C |date=2012 |publisher=Routledge |isbn=978-0-415-89867-6}} Bruch's theories tend to dominate popular thinking. A further important event was the death of the popular singer and drummer Karen Carpenter in 1983, which prompted widespread ongoing media coverage of eating disorders.{{cite news |date=29 March 2016|title=Anorexia: you don't just grow out of it |newspaper=The Guardian |url=https://www.theguardian.com/society/2016/mar/29/anorexia-you-dont-just-grow-out-of-it |url-status=live |access-date=29 March 2016 |archive-url=https://web.archive.org/web/20160329055732/http://www.theguardian.com/society/2016/mar/29/anorexia-you-dont-just-grow-out-of-it |archive-date=29 March 2016 |vauthors=Arnold C}}

• Body image
• Eating recovery
• Evolutionary psychiatry
• Idée fixe
• Inedia
• List of people with anorexia nervosa
• National Association of Anorexia Nervosa and Associated Disorders
• Muscle dysmorphia
• Orthorexia nervosa
• Pro-ana

{{Reflist}}

File:Why do anorexia patients feel fat.webm)]]

{{refbegin}}

• {{cite journal |vauthors=Bailey AP, Parker AG, Colautti LA, Hart LM, Liu P, Hetrick SE |title=Mapping the evidence for the prevention and treatment of eating disorders in young people |journal=Journal of Eating Disorders |volume=2 |issue=1 |pages=5 |year=2014 |pmid=24999427 |pmc=4081733 |doi=10.1186/2050-2974-2-5 |ref=none |doi-access=free}}
• {{cite journal |vauthors=Coelho GM, Gomes AI, Ribeiro BG, Soares E |title=Prevention of eating disorders in female athletes |journal=Open Access Journal of Sports Medicine |volume=5 |pages=105–113 |year=2014 |pmid=24891817 |pmc=4026548 |doi=10.2147/OAJSM.S36528 |ref=none |doi-access=free}}
• {{cite journal |vauthors=Luca A, Luca M, Calandra C |title=Eating Disorders in Late-life |journal=Aging and Disease |volume=6 |issue=1 |pages=48–55 |date=February 2015 |pmid=25657852 |pmc=4306473 |doi=10.14336/AD.2014.0124 |ref=none}}

{{refend}}

{{Commons category|Anorexia nervosa}}

{{Wikiquote}}

• [https://anad.org/ National Association of Anorexia Nervosa and Associated Disorders]
• [https://div12.org/psychological-treatments/disorders/anorexia-nervosa/ Society of Clinical Psychology—Anorexia]

{{Medical condition classification and resources

| DiseasesDB = 749

| ICD10 = {{ICD10|F|50|0|f|50}}-{{ICD10|F|50|1|f|50}}

| ICD9 = {{ICD9|307.1}}

| ICDO =

| OMIM = 606788

| MedlinePlus = 000362

| eMedicineSubj = emerg

| eMedicineTopic = 34

| eMedicine_mult = {{eMedicine2|med|144}}

| MeshID = D000856

}}

{{Psychiatry}}

{{Digital media use and mental health}}

{{Authority control}}

Category:Wikipedia medicine articles ready to translate

Category:Wikipedia neurology articles ready to translate

Category:Articles containing video clips

Category:Eating disorders