Classification of obesity#Body Volume Index

Obesity is a medical condition in which excess body fat has accumulated to the extent that it has an adverse effect on health.{{rp|6}} Relative weight{{clarify |date =May 2019}} and body mass index (BMI) are nearly identical and are reasonable estimates of body fatness as measured by percentage body fat.{{cite journal | vauthors = Gray DS, Fujioka K | title = Use of relative weight and Body Mass Index for the determination of adiposity | journal = Journal of Clinical Epidemiology | volume = 44 | issue = 6 | pages = 545–550 | year = 1991 | pmid = 2037859 | doi = 10.1016/0895-4356(91)90218-X }} However, BMI does not account for the wide variation in body fat distribution, and may not correspond to the same degree of fatness or associated health risk in different individuals and populations.{{rp|7}}{{cite journal | vauthors = Sweeting HN | title = Measurement and definitions of obesity in childhood and adolescence: a field guide for the uninitiated | journal = Nutrition Journal | volume = 6 | issue = 1 | pages = 32 | date = October 2007 | pmid = 17963490 | pmc = 2164947 | doi = 10.1186/1475-2891-6-32 | doi-access = free }}{{rp|xiv}} Other measurements of fat distribution include the waist–hip ratio and body fat percentage. Normal weight obesity is a condition of having normal body weight, but high body fat percentages with the same health risks of obesity.[http://www.mayoclinic.org/news2008-rst/4738.html Normal Weight Obesity: An Emerging Risk Factor for Heart and Metabolic Problems]. Mayo Clinic. March 27, 2008.{{cite web | vauthors = Zeratsky K | url = http://www.mayoclinic.com/health/normal-weight-obesity/AN02007 | title = Normal weight obesity: A hidden health risk? | quote = Can you be considered obese if you have a normal body weight? | work = Mayo Clinic - Obesity Expert Answers | access-date = 5 August 2009 | date = 25 January 2010 }} BMI can be used to predict the risk of metabolic abnormalities like diabetes.{{cite journal | vauthors = Vazquez G, Duval S, Jacobs DR, Silventoinen K | title = Comparison of body mass index, waist circumference, and waist/hip ratio in predicting incident diabetes: a meta-analysis | journal = Epidemiologic Reviews | volume = 29 | issue = 1 | pages = 115–128 | date = 2 May 2007 | pmid = 17494056 | doi = 10.1093/epirev/mxm008 | doi-access = free }}

{{main|Body mass index}}

Body mass index or BMI is a simple and widely used method for estimating body fat mass.{{cite journal | vauthors = Mei Z, Grummer-Strawn LM, Pietrobelli A, Goulding A, Goran MI, Dietz WH | title = Validity of body mass index compared with other body-composition screening indexes for the assessment of body fatness in children and adolescents | journal = The American Journal of Clinical Nutrition | volume = 75 | issue = 6 | pages = 978–985 | date = June 2002 | pmid = 12036802 | doi = 10.1093/ajcn/75.6.978 | doi-access = free }} BMI was developed in the 19th century by the Belgian statistician and anthropometrist Adolphe Quetelet.{{cite book | vauthors = Quetelet LA | year=1871 | title=Antropométrie ou Mesure des Différences Facultés de l'Homme | location=Brussels | publisher=Musquardt}} BMI is an accurate reflection of body fat percentage in the majority of the adult population. However it is less accurate in people such as body builders and pregnant women.{{rp|60}} A formula combining BMI, age, and gender can be used to estimate a person's body fat percentage to an accuracy of 4%.{{cite book | vauthors = Seidell JC | chapter = Epidemiology — definition and classification of obesity | veditors = Kopelman PG, Caterson ID, Stock MJ, Dietz WH |title=Clinical obesity in adults and children: In Adults and Children |publisher=Blackwell Publishing |year=2005 |pages=[https://archive.org/details/clinicalobesityi02edunse/page/3 3–11] |isbn=978-1-4051-1672-5 |chapter-url=https://archive.org/details/clinicalobesityi02edunse/page/3 }}

An alternative method, body volume index (BVI), is being developed by Mayo Clinic in an effort to better take into account different body shapes.{{cite journal | vauthors = Romero-Corral A, Somers V, Lopez-Jimenez F, Korenfeld Y, Palin S, Boclaert K, Boarin S, Sierra-Johnson J, Rahirn A | title = 3-D Body Scanner, Body Volume Index: A Novel, Reproducible and Automated Anthropometric Tool Associated with Cardiometabolic Biomarkers | journal = Obesity | date = October 2008 | volume = 16 | issue = 1 | pages = S124 | publisher = Nature Publishing Group }} BVI measures body fat distribution and calculates the BVI number, based on these results. This BVI number is an indication of weight associated health risk.

BMI is calculated by dividing the subject's mass by the square of their height, typically expressed either in metric or US "Customary" units:

:Metric: $\backslash mathrm\{BMI\}=\backslash frac\{\backslash mathrm\{kilograms\}\}\{\backslash mathrm\{meters\}^2\}$

:US/Customary and imperial: $\backslash mathrm\{BMI\}=\backslash mathrm\{pounds\}\backslash frac\{703\}\{\backslash mathrm\{inches\}^2\}$

The most commonly used definitions, established by the World Health Organization (WHO) in 1997 and published in 2000, provide the values listed in the table at right.{{rp|9}}

Some modifications to the WHO definitions have been made by particular bodies. The surgical literature breaks down class III obesity into further categories, though the exact values are still disputed.{{cite journal | vauthors = Sturm R | title = Increases in morbid obesity in the USA: 2000-2005 | journal = Public Health | volume = 121 | issue = 7 | pages = 492–496 | date = July 2007 | pmid = 17399752 | pmc = 2864630 | doi = 10.1016/j.puhe.2007.01.006 }}

• Any BMI ≥ 35 is severe obesity
• A BMI of ≥ 40 is morbid obesity
• A BMI of ≥ 50 is extreme obesity

As Asian populations develop negative health consequences at a lower BMI than Western populations, some nations have redefined obesity. The Japanese have defined obesity as any BMI greater than 25{{cite journal | vauthors = Kanazawa M, Yoshiike N, Osaka T, Numba Y, Zimmet P, Inoue S | title = Criteria and classification of obesity in Japan and Asia-Oceania | journal = Asia Pacific Journal of Clinical Nutrition | volume = 11 | issue = Suppl 8 | pages = S732–S737 | date = December 2002 | pmid = 12534701 | doi = 10.1046/j.1440-6047.11.s8.19.x }} while China defines it as any BMI of greater than 28.{{cite journal | vauthors = Bei-Fan Z | collaboration = Cooperative Meta-Analysis Group of Working Group on Obesity in China |title=Predictive values of body mass index and waist circumference for risk factors of certain related diseases in Chinese adults: study on optimal cut-off points of body mass index and waist circumference in Chinese adults |journal=Asia Pac J Clin Nutr |volume=11 |pages=S685–93 |date=December 2002 |issue=Suppl 8 |doi= 10.1046/j.1440-6047.11.s8.9.x}}

The BMI-based definition is easy to use and it is particularly convenient for statistical purposes, since it only depends on two commonly measured quantities, one's height and weight. However, it ignores variations between individuals in amounts of lean body mass, particularly muscle mass. Individuals involved in heavy physical labor or sports may have high BMI values despite having little fat. For example, more than half of all NFL players are classified as "obese" (BMI ≥ 30), and 1 in 4 are classified as "extremely obese" (BMI ≥ 35), according to the BMI metric.{{cite web | editor = Brakeville R | date = 13 September 2023 | work = WebMD |url=http://www.webmd.com/fitness-exercise/news/20050301/many-nfl-players-fatter-than-couch-potatoes|title=Many NFL Players Fatter Than Couch Potatoes}} However, their mean body fat percentage, 14%, is well within what is considered a healthy range.{{cite web | date = 26 May 2009 | work = U.S. News & World Report | vauthors = Edelson E |url=http://health.usnews.com/health-news/family-health/heart/articles/2009/05/26/nfl-players-not-at-increased-heart-risk|title=NFL Players Not at Increased Heart Risk: Study finds they showed no more signs of cardiovascular trouble than general male population}}

The preferred obesity metric in scholarly circles is the body fat percentage (BF%){{Citation needed|date=February 2025}} - the ratio of the total weight of person's fat to his or her body weight, and BMI is viewed merely as a way to approximate BF%.{{cite journal | vauthors = Seidell JC, Flegal KM | title = Assessing obesity: classification and epidemiology | journal = British Medical Bulletin | volume = 53 | issue = 2 | pages = 238–52 | date = 1997 | pmid = 9246834 | doi = 10.1093/oxfordjournals.bmb.a011611 }} Levels in excess of 32% for women and 25% for men are generally considered to indicate obesity.

Sumo wrestlers may be categorized by BMI as "severely obese" or "very severely obese" but many Sumo wrestlers are not categorized as obese when body fat percentage is used instead (having <25% body fat).{{cite journal | vauthors = Yamauchi T, Abe T, Midorikawa T, Kondo M |title=Body composition and resting metabolic rate of Japanese college Sumo wrestlers and non-athlete students: are Sumo wrestlers obese? |journal=Anthropological Science |date=2004 |volume=112 |issue=2|pages=179–185 |doi=10.1537/ase.040210 |doi-access=free }} Some Sumo wrestlers were found to have no more body fat than a non-Sumo comparison group, with high BMI values resulting from their high amounts of lean body mass.

However, accurate measurement of body fat percentage is much more difficult than measurement of BMI. Several methods of varying accuracy and complexity exist.

Other proposed but less common obesity measures include waist circumference and waist–hip ratio. These measure a common form of obesity known as abdominal or central obesity, characterized by excess deposits of fat in the abdominal region and inside peritoneal cavity. They have been shown to be comparable to BMI in their power to predict the risk of metabolic abnormalities such as type II diabetes, and possibly superior to BMI as predictors of cardiovascular disease.{{cite journal | vauthors = Huxley R, Mendis S, Zheleznyakov E, Reddy S, Chan J | title = Body mass index, waist circumference and waist:hip ratio as predictors of cardiovascular risk--a review of the literature | journal = European Journal of Clinical Nutrition | volume = 64 | issue = 1 | pages = 16–22 | date = January 2010 | pmid = 19654593 | doi = 10.1038/ejcn.2009.68 | s2cid = 205129856 | doi-access = }}

File:Preclinical and Clinical Obesity.jpg

In January of 2025, a group of 58 experts on obesity published a consensus article offering a new definition and classification for obesity.{{cite journal | vauthors = Rubino F, Cummings DE, Eckel RH, Cohen RV, Wilding JP, Brown WA, Stanford FC, Batterham RL, Farooqi IS, Farpour-Lambert NJ, le Roux CW, Sattar N, Baur LA, Morrison KM, Misra A, Kadowaki T, Tham KW, Sumithran P, Garvey WT, Kirwan JP, Fernández-Real JM, Corkey BE, Toplak H, Kokkinos A, Kushner RF, Branca F, Valabhji J, Blüher M, Bornstein SR, Grill HJ, Ravussin E, Gregg E, Al Busaidi NB, Alfaris NF, Al Ozairi E, Carlsson LM, Clément K, Després JP, Dixon JB, Galea G, Kaplan LM, Laferrère B, Laville M, Lim S, Luna Fuentes JR, Mooney VM, Nadglowski J, Urudinachi A, Olszanecka-Glinianowicz M, Pan A, Pattou F, Schauer PR, Tschöp MH, van der Merwe MT, Vettor R, Mingrone G | title = Definition and diagnostic criteria of clinical obesity | journal = The Lancet. Diabetes & Endocrinology | volume = 13 | issue = 3 | pages = 221–262 | date = March 2025 | pmid = 39824205 | pmc = 11870235 | doi = 10.1016/S2213-8587(24)00316-4 | pmc-embargo-date = March 1, 2026 }}{{Cite web |date=2025-01-14 |title=Moving away from BMI, experts propose a new definition for obesity |url=https://apnews.com/article/obesity-bmi-weight-definition-lancet-f3aafc072a3e685036d32ce3d9c3adac |access-date=2025-03-31 |website=AP News |language=en}} They propose a new classification of preclinical and clinical obesity, in this model there is no designation of overweight. For this classification, BMI as well as other measures such as waist circumference are taken into account as well as a patient's other weight related co-morbidities. {{Cite web |date=2025-01-15 |title=Obesity won't be solely defined by BMI under new plan for diagnosis by global experts |url=https://www.pbs.org/newshour/health/obesity-wont-be-solely-defined-by-bmi-under-new-plan-for-diagnosis-by-global-experts |access-date=2025-03-18 |website=PBS News |language=en-us}} For a diagnosis of obesity patients must have evidence of excess adiposity as found in one of three ways as 1) measured by dual-energy X-ray absorptiometry, or 2) combination of BMI with one other physical measurement such as waist circumference, waist to hip ratio, or waist to height ratio, or by 3) combination of two of the aforementioned measurements without use of BMI. To differentiate between preclinical and clinical obesity there must be evidence of tissue or organ disfunction or a reduction in a person's ability to perform activities of daily living due to this excess adiposity. If evidence of such dysfunction or limitation is found in an individual who has obesity, they will meet criteria for the new diagnosis of clinical obesity. If no evidence is found then the diagnosis of preclinical obesity is given to indicate that they are still at risk for developing such dysfunction in the future. This model is new and how it will be applied clinically is still uncertain.

{{Main|Abdominal obesity|Waist-to-height ratio}}

In the United States a waist circumference of >102 cm (≈40") in men and >88 cm (≈34.5") in women{{cite journal | vauthors = Janssen I, Katzmarzyk PT, Ross R | title = Body mass index, waist circumference, and health risk: evidence in support of current National Institutes of Health guidelines | journal = Archives of Internal Medicine | volume = 162 | issue = 18 | pages = 2074–2079 | date = October 2002 | pmid = 12374515 | doi = 10.1001/archinte.162.18.2074 | doi-access = }} or the waist–hip ratio (the circumference of the waist divided by that of the hips) of >0.9 for men and >0.85 for women are used to define central obesity.

In the European Union waist circumference of ≥ 94 cm(≈37") in men and ≥ 80 cm(≈31.5") in non-pregnant women are used as cut offs for central obesity.{{cite journal | vauthors = Tsigos C, Hainer V, Basdevant A, Finer N, Fried M, Mathus-Vliegen E, Micic D, Maislos M, Roman G, Schutz Y, Toplak H, Zahorska-Markiewicz B | title = Management of obesity in adults: European clinical practice guidelines | journal = Obesity Facts | volume = 1 | issue = 2 | pages = 106–116 | date = April 2008 | pmid = 20054170 | pmc = 6452117 | doi = 10.1159/000126822 | collaboration = Obesity Management Task Force of the European Association for the Study of Obesity }}

A lower cut off of 90 cm has been recommended for South Asian and Chinese men, while a cut off of 85 cm has been recommended for Japanese men.

In those with a BMI under 35, intra-abdominal body fat is related to negative health outcomes independent of total body fat.{{cite book |author=U.S. Preventive Services Task Force Evidence Syntheses|title=HSTAT: Guide to Clinical Preventive Services, 3rd Edition: Recommendations and Systematic Evidence Reviews, Guide to Community Preventive Services |year=2000 |url=https://www.ncbi.nlm.nih.gov/books/bv.fcgi?rid=hstat3.section.36199}} Intra-abdominal or visceral fat has a particularly strong correlation with cardiovascular disease.{{cite journal | vauthors = Yusuf S, Hawken S, Ounpuu S, Dans T, Avezum A, Lanas F, McQueen M, Budaj A, Pais P, Varigos J, Lisheng L | title = Effect of potentially modifiable risk factors associated with myocardial infarction in 52 countries (the INTERHEART study): case-control study | journal = Lancet | volume = 364 | issue = 9438 | pages = 937–952 | year = 2004 | pmid = 15364185 | doi = 10.1016/S0140-6736(04)17018-9 | hdl-access = free | s2cid = 30811593 | hdl = 10983/21615 }} In a study of 15,000 people, waist circumference also correlated better with metabolic syndrome than BMI.{{cite journal | vauthors = Janssen I, Katzmarzyk PT, Ross R | title = Waist circumference and not body mass index explains obesity-related health risk | journal = The American Journal of Clinical Nutrition | volume = 79 | issue = 3 | pages = 379–384 | date = March 2004 | pmid = 14985210 | doi = 10.1093/ajcn/79.3.379 | doi-access = free }} Women with abdominal obesity have a cardiovascular risk similar to that of men.{{cite journal | vauthors = Larsson B, Bengtsson C, Björntorp P, Lapidus L, Sjöström L, Svärdsudd K, Tibblin G, Wedel H, Welin L, Wilhelmsen L | title = Is abdominal body fat distribution a major explanation for the sex difference in the incidence of myocardial infarction? The study of men born in 1913 and the study of women, Göteborg, Sweden | journal = American Journal of Epidemiology | volume = 135 | issue = 3 | pages = 266–273 | date = February 1992 | pmid = 1546702 | doi = 10.1093/oxfordjournals.aje.a116280 }} In people with a BMI over 35, measurement of waist circumference however adds little to the predictive power of BMI as most individuals with this BMI have abnormal waist circumferences.{{cite book | title = Morbidity and Mortality: 1998 Chartbook on Cardiovascular, Lung and Blood Diseases. | publisher = National Institutes of Health, National Heart Lung and Blood Institute | location = Bethesda, MD | date = October 1998 | page = 61 }}

The Body Volume Index (BVI) is a novel method for calculating body fat distribution. Human body volumes and body volume ratios and their links to body compositions have been researched for several years.{{cite journal | vauthors = Wells JC, Douros I, Fuller NJ, Elia M, Dekker L | title = Assessment of body volume using three-dimensional photonic scanning | journal = Annals of the New York Academy of Sciences | volume = 904 | issue = 1| pages = 247–54 | date = May 2000 | pmid = 10865749 | doi = 10.1111/j.1749-6632.2000.tb06460.x | bibcode = 2000NYASA.904..247W }}{{cite journal | vauthors = Olivares J, Wang J, Yu W, Pereg V, Weil R, Kovacs B, Gallagher D, Pi-Sunyer FX | title = Comparisons of body volumes and dimensions using three-dimensional photonic scanning in adult Hispanic-Americans and Caucasian-Americans | journal = Journal of Diabetes Science and Technology | volume = 1 | issue = 6 | pages = 921–928 | date = November 2007 | pmid = 19885167 | pmc = 2769678 | doi = 10.1177/193229680700100619 }} Later the term Body Volume Index (BVI) instead of ratio was introduced by Select Research and Mayo Clinic; BVI has been developed as an alternative to BMI.{{Cite web|url=https://news.mayocliniclabs.com/2017/05/05/week-review-may-5/|title=Week in Review: May 5|date=2017-05-05| work = Insights | publisher = Mayo Clinic |language=en-US|access-date=2019-05-07|archive-url=https://web.archive.org/web/20190507140633/https://news.mayocliniclabs.com/2017/05/05/week-review-may-5/|archive-date=2019-05-07|url-status=dead}}{{Cite web |url=http://www.bodyvolume.com/about-bvi/ |title=About BVI |access-date=2018-06-20 |archive-url=https://web.archive.org/web/20180620124815/http://www.bodyvolume.com/about-bvi/ | publisher = BVI - America, LLC |archive-date=2018-06-20 |url-status=dead }} BMI doesn't account for muscle and fat distribution, or gender, or ethnicity; and therefore is not an accurate measure of obesity in many individuals. BVI uses 3D technology to analyse overall body shape, identifying where fat is distributed across the body.{{cite journal | vauthors = Tahrani A, Boelaert K, Barnes R, Palin S, Field A, Redmayne H, Aytok L, Rahim A | title = Body volume index: time to replace body mass index?. | journal = Endocrine Abstracts | date = April 2008 | volume = 15 | page = 104 | publisher = Bioscientifica | url = https://www.endocrine-abstracts.org/ea/0015/ea0015P104 }}

Body Volume means the composition of a person and their body parts; each part of a person's body (arms, legs, chest, etc.) has its own 3D shape, individual weight and measurement. An increase in the volume of fat and muscle normally corresponds with an increase or decrease of volume in that area of the body. BVI calculates a person's body fat composition from two images taken front and side on. A silhouette is extracted from these images and a 3D model created, from which detailed linear and volume measurements can be calculated. By comparing the 3D models to MRI data, BVI software is able to calculate fat distribution, and in particular visceral fat accumulated near the individual's organs. The results will provide accurate measurements for waist and hip circumferences, waist to hip ratio, total body fat, visceral fat and BVI number.

The BVI Number has been designed by Mayo Clinic as an alternative to the BMI number. The BVI algorithm also accounts for demographic factors, such as age and gender, and is based on weight distribution across different parts of the body. The BVI is expressed as a single numerical value on a scale from 1 to 20. A higher BVI number indicates a higher calculated risk for cardio-metabolic complications and other health risks associated with body fat distribution. A BVI score below 13 is considered lower-risk, while scores above 13 are associated with increased risk, accounting for the tendency of risk to increase with age. It provides an indication of health risk based on fat distribution with a particular emphasis on visceral fat; which is located around organs. Visceral fat is metabolically active, with high levels a known risk factor for metabolic disease which includes cardiovascular disease{{cite journal | vauthors = Van Gaal LF, Mertens IL, De Block CE | title = Mechanisms linking obesity with cardiovascular disease | journal = Nature | volume = 444 | issue = 7121 | pages = 875–880 | date = December 2006 | pmid = 17167476 | doi = 10.1038/nature05487 }} and diabetes type II.{{cite journal | vauthors = Kahn SE, Hull RL, Utzschneider KM | author-link1 = Steven Kahn (endocrinologist) | title = Mechanisms linking obesity to insulin resistance and type 2 diabetes | journal = Nature | volume = 444 | issue = 7121 | pages = 840–846 | date = December 2006 | pmid = 17167471 | doi = 10.1038/nature05482 }}

{{Main|Body fat percentage}}

File:FatCT2008.JPG. Note the 3.6 cm (1.4 inches) of subcutaneous fat on the obese person. Some obese people would present on abdominal CT with visceral fat and negligible subcutaneous fat instead.{{cite journal | vauthors = Bazzocchi A, Diano D, Battista G | title = How fat is fat? | journal = Lancet | volume = 380 | issue = 9837 | pages = e1 | date = July 2012 | pmid = 22484135 | doi = 10.1016/S0140-6736(11)61925-9 | s2cid = 205964850 | doi-access = free }}]]

Body fat percentage is total body fat expressed as a percentage of total body weight. There is no generally accepted definition of obesity based on total body fat. Most researchers have used >25% in men, and >30% in women, as cut-points to define obesity,{{cite journal | vauthors = Okorodudu DO, Jumean MF, Montori VM, Romero-Corral A, Somers VK, Erwin PJ, Lopez-Jimenez F | title = Diagnostic performance of body mass index to identify obesity as defined by body adiposity: a systematic review and meta-analysis | journal = International Journal of Obesity | volume = 34 | issue = 5 | pages = 791–799 | date = May 2010 | pmid = 20125098 | doi = 10.1038/ijo.2010.5 | s2cid = 11456962 | doi-access = }} but the use of these values have been disputed.{{cite journal | vauthors = Ho-Pham LT, Campbell LV, Nguyen TV | title = More on body fat cutoff points | journal = Mayo Clinic Proceedings | volume = 86 | issue = 6 | pages = 584; author reply 584-584; author reply 585 | date = June 2011 | pmid = 21628621 | pmc = 3104919 | doi = 10.4065/mcp.2011.0097 }}

As by anthropometric methods, body fat percentage can be estimated from a person's BMI by the following formula:[https://www.livestrong.com/article/173592-how-to-convert-bmi-to-body-fat-percentage/ How to Convert BMI to Body Fat Percentage]. By Jessica Bruso with reference to a study published in the International Journal of Obesity and Related Metabolic Disorders in 2002. July 18, 2017.

:$\backslash text\{(Adult)\; body\; fat\; percentage\}\; =\; (1.39\; \backslash times\; \backslash text\{BMI\})\; +\; (0.16\; \backslash times\; \backslash text\{age\})\; -\; (10.34\; \backslash times\; \backslash text\{gender\})\; -\; 9$

:where gender (sex) is 0 if female and 1 if male to account for the lower body fat percentage of men.

There are many other methods used to determine body fat percentage. Hydrostatic weighing, one of the most accurate methods of body fat calculation, involves weighing a person underwater. Two other simpler and less accurate methods have been used historically but are now not recommended.{{cite web |url=http://www.nice.org.uk/nicemedia/pdf/CG43NICEGuideline.pdf |title=Obesity: guidance on the prevention, identification, assessment and management of overweight and obesity in adults and children |publisher=National Health Services (NHS)|year= 2006|work=National Institute for Health and Clinical Excellence(NICE)|access-date=April 8, 2009 | page = 36 }} The first is the skinfold test, in which a pinch of skin is precisely measured to determine the thickness of the subcutaneous fat layer.{{cite book | vauthors = Jebb S, Wells J | chapter = Measuring body composition in adults and children | veditors = Kopelman PG, Caterson ID, Stock MJ, Dietz WH |title=Clinical obesity in adults and children: In Adults and Children |publisher=Blackwell Publishing |year=2005 |pages=[https://archive.org/details/clinicalobesityi02edunse/page/12 12–28] |isbn=978-1-4051-1672-5 |chapter-url=https://archive.org/details/clinicalobesityi02edunse/page/12 }}{{rp|16}} The other is bioelectrical impedance analysis which uses electrical resistance. Bioelectrical impedance has not been shown to provide an advantage over BMI.

Body fat percentage measurement techniques used mainly for research include computed tomography (CT scan), magnetic resonance imaging (MRI), and dual energy X-ray absorptiometry (DEXA). These techniques provide very accurate measurements, but it can be difficult to obtain in the severely obese due to weight limits of most equipment and insufficient diameter of many CT or MRI scanners.{{rp|20}}

{{Main|Childhood obesity}}

The healthy BMI range varies with the age and sex of the child. Obesity in children and adolescents is defined as a BMI greater than the 95th percentile.{{cite web |url=https://www.cdc.gov/nccdphp/dnpa/healthyweight/assessing/bmi/childrens_BMI/about_childrens_BMI.htm |title=Healthy Weight: Assessing Your Weight: BMI: About BMI for Children and Teens|publisher=Center for disease control and prevention|access-date=April 6, 2009}} The reference data that these percentiles are based on is from 1963 to 1994 and thus has not been affected by the recent increases in rates of obesity.{{cite journal | vauthors = Flegal KM, Ogden CL, Wei R, Kuczmarski RL, Johnson CL | title = Prevalence of overweight in US children: comparison of US growth charts from the Centers for Disease Control and Prevention with other reference values for body mass index | journal = The American Journal of Clinical Nutrition | volume = 73 | issue = 6 | pages = 1086–1093 | date = June 2001 | pmid = 11382664 | doi = 10.1093/ajcn/73.6.1086 | doi-access = free }}

Childhood obesity has reached epidemic proportions in the 21st century with rising rates in both the developed and developing world.{{Citation needed|date=January 2011}} Rates of obesity in Canadian boys have increased from 11% in the 1980s to over 30% in the 1990s, while during this same time period rates increased from 4 to 14% in Brazilian children.

As with obesity in adults many different factors contribute to the rising rates of childhood obesity. Changing diet and decreasing physical activity are believed to be the two most important in causing the recent increase in the rate of obesity. Activities from self-propelled transport, to school physical education, and organized sports has been declining in many countries.{{cite journal | vauthors = Dollman J, Norton K, Norton L | title = Evidence for secular trends in children's physical activity behaviour | journal = British Journal of Sports Medicine | volume = 39 | issue = 12 | pages = 892–7; discussion 897 | date = December 2005 | pmid = 16306494 | pmc = 1725088 | doi = 10.1136/bjsm.2004.016675 }}

Because childhood obesity often persists into adulthood, and is associated with numerous chronic illnesses, it is important that children who are obese be tested for hypertension, diabetes, hyperlipidemia, and fatty liver.{{cite journal | vauthors = Fennoy I |title=Childhood Obesity, Part 1: Weight Evaluation and Comorbidity Screening |journal=Consultant for Pediatricians |date=October 1, 2008 |url=http://www.consultantlive.com/cholesterol/article/1145470/1403931 |access-date=October 21, 2009 |archive-date=August 4, 2009 |archive-url=https://web.archive.org/web/20090804024401/http://www.consultantlive.com/cholesterol/article/1145470/1403931 |url-status=dead }}

Treatments used in children are primarily lifestyle interventions and behavioral techniques. Medications are not FDA approved for use in this age group.{{cite journal | vauthors = Flynn MA, McNeil DA, Maloff B, Mutasingwa D, Wu M, Ford C, Tough SC | title = Reducing obesity and related chronic disease risk in children and youth: a synthesis of evidence with 'best practice' recommendations | journal = Obesity Reviews | volume = 7 | issue = Suppl 1 | pages = 7–66 | date = February 2006 | pmid = 16371076 | doi = 10.1111/j.1467-789X.2006.00242.x | doi-access = }}

== See also ==

• {{annotated link|Allometry}}
• {{annotated link|Body adiposity index}} (BAI)
• {{annotated link|Body fat percentage}} (BFP)
• {{annotated link|Body mass index}} (BMI)
• {{annotated link|Body mass index#BMI prime|Body mass index Prime}}
• {{annotated link|Body roundness index}}
• {{annotated link|Body Shape Index}}
• {{annotated link|Body Volume Index}}
• {{annotated link|Body water}}
• {{annotated link|Corpulence index}}
• {{annotated link|List of countries by Body Mass Index (BMI)}}
• {{annotated link|Obesity paradox}}
• {{annotated link|Pignet Index}}
• {{annotated link|Relative Fat Mass}}
• {{annotated link|Sagittal Abdominal Diameter}}
• {{annotated link|Waist–hip ratio}}
• {{annotated link|Waist-to-height ratio}}

{{reflist}}

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• {{cite book | vauthors = Puhl R, Henderson K, Brownell K | chapter = Social consequences of obesity | veditors = Kopelman PG, Caterson ID, Stock MJ, Dietz WH |title=Clinical obesity in adults and children: In Adults and Children |publisher=Blackwell Publishing |year=2005 |pages=[https://archive.org/details/clinicalobesityi02edunse/page/29 29–45] |isbn=978-1-4051-1672-5 |chapter-url=https://archive.org/details/clinicalobesityi02edunse/page/29 }}
• {{cite book | vauthors = Kopelman P, Caterson I | chapter = An overview of obesity management | veditors = Kopelman PG, Caterson ID, Stock MJ, Dietz WH |title=Clinical obesity in adults and children: In Adults and Children |publisher=Blackwell Publishing |year=2005 |pages=[https://archive.org/details/clinicalobesityi02edunse/page/319 319–326] |isbn=978-1-4051-1672-5 |chapter-url=https://archive.org/details/clinicalobesityi02edunse/page/319 }}

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{{Obesity}}