Obesity classification: Difference between revisions
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In a ''clinical'' setting, physicians take into account race, ethnicity, lean mass (muscularity), age, sex, and other factors which can affect the interpretation of BMI. BMI overestimates body fat in persons who are very muscular, and it can underestimate body fat in persons who have lost body mass (e.g. many elderly).<ref name=NHLBI/> Mild obesity as defined by BMI alone is not a cardiac risk factor, and hence BMI cannot be used as a sole clinical and epidemiological predictor of cardiovascular health.<ref>{{cite journal |author=Romero-Corral A, Montori VM, Somers VK, ''et al'' |title=Association of bodyweight with total mortality and with cardiovascular events in coronary artery disease: a systematic review of cohort studies |journal=Lancet |volume=368 |issue=9536 |pages=666–78 |year=2006 |pmid=16920472 |doi=10.1016/S0140-6736(06)69251-9}}</ref> | In a ''clinical'' setting, physicians take into account race, ethnicity, lean mass (muscularity), age, sex, and other factors which can affect the interpretation of BMI. BMI overestimates body fat in persons who are very muscular, and it can underestimate body fat in persons who have lost body mass (e.g. many elderly).<ref name=NHLBI/> Mild obesity as defined by BMI alone is not a cardiac risk factor, and hence BMI cannot be used as a sole clinical and epidemiological predictor of cardiovascular health.<ref>{{cite journal |author=Romero-Corral A, Montori VM, Somers VK, ''et al'' |title=Association of bodyweight with total mortality and with cardiovascular events in coronary artery disease: a systematic review of cohort studies |journal=Lancet |volume=368 |issue=9536 |pages=666–78 |year=2006 |pmid=16920472 |doi=10.1016/S0140-6736(06)69251-9}}</ref> | ||
===Body fat measurement=== | ===Body fat measurement=== | ||
Revision as of 15:41, 27 August 2012
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Obesity Microchapters |
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Diagnosis |
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Treatment |
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Lifestyle Intervention and Counseling (Comprehensive Lifestyle Intervention) |
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Case Studies |
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USPSTF Recommendations and Guidelines on Management of Obesity |
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2017 Guidelines for Screening of Obesity in Children and Adolescents |
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AHA/ACC/TOS Guidelines on Management of Overweight and Obesity |
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2013 AHA/ACC/TOS Guidelines on Management of Overweight and Obesity |
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Obesity classification On the Web |
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American Roentgen Ray Society Images of Obesity classification |
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Risk calculators and risk factors for Obesity classification |
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Overview
Classification
Obesity can be defined in absolute or relative terms. In practical settings, obesity is typically evaluated in absolute terms by measuring BMI (body mass index), but also in terms of its distribution through waist circumference or waist-hip circumference ratio measurements.[1] In addition, the presence of obesity needs to be regarded in the context of other risk factors and comorbidities (other medical conditions that could influence risk of complications).[2]
BMI
BMI, or body mass index, is a simple and widely used method for estimating body fat.[3] BMI was developed by the Belgian statistician and anthropometrist Adolphe Quetelet.[4] It is calculated by dividing the subject's weight by the square of his/her height, typically expressed either in metric or US "Customary" units:
- Metric: <math>BMI = kg/m^2</math>
Where <math>kg</math> is the subject's weight in kilograms and <math>m</math> is the subject's height in metres.
- US/Customary: <math>BMI=lb*703/in^2</math>
Where <math>lb</math> is the subject's weight in pounds and <math>in</math> is the subject's height in inches.
The current definitions commonly in use establish the following values, agreed in 1997 and published in 2000:[5]
- A BMI less than 18.5 is underweight
- A BMI of 18.5–24.9 is normal weight
- A BMI of 25.0–29.9 is overweight
- A BMI of 30.0–39.9 is obese
- A BMI of 40.0 or higher is severely (or morbidly) obese
- A BMI of 35.0 or higher in the presence of at least one other significant comorbidity is also classified by some bodies as morbid obesity.[6][7]
In a clinical setting, physicians take into account race, ethnicity, lean mass (muscularity), age, sex, and other factors which can affect the interpretation of BMI. BMI overestimates body fat in persons who are very muscular, and it can underestimate body fat in persons who have lost body mass (e.g. many elderly).[2] Mild obesity as defined by BMI alone is not a cardiac risk factor, and hence BMI cannot be used as a sole clinical and epidemiological predictor of cardiovascular health.[8]
Body fat measurement
An alternative way to determine obesity is to assess percent body fat. Doctors and scientists generally agree that men with more than 25% body fat and women with more than 30% body fat are obese. However, it is difficult to measure body fat precisely. The most accepted method has been to weigh a person underwater, but underwater weighing is a procedure limited to laboratories with special equipment. Two simpler methods for measuring body fat are the skinfold test, in which a pinch of skin is precisely measured to determine the thickness of the subcutaneous fat layer; or bioelectrical impedance analysis, usually only carried out at specialist clinics. Their routine use is discouraged.[9]
Other measurements of body fat include computed tomography (CT/CAT scan), magnetic resonance imaging (MRI/NMR), and dual energy X-ray absorptiometry (DXA).[10]
References
- ↑ Sweeting HN (2007). "Measurement and definitions of obesity in childhood and adolescence: a field guide for the uninitiated". Nutr J. 6: 32. doi:10.1186/1475-2891-6-32. PMID 17963490.
- ↑ 2.0 2.1 National Heart, Lung, and Blood Institute. Clinical Guidelines on the Identification, Evaluation, and Treatment of Overweight and Obesity in Adults (PDF). International Medical Publishing, Inc. ISBN 1-58808-002-1.
- ↑ Mei Z, Grummer-Strawn LM, Pietrobelli A, Goulding A, Goran MI, Dietz WH. Validity of body mass index compared with other body-composition screening indexes for the assessment of body fatness in children and adolescents. Am J Clin Nutr 2002;75:978-85. PMID 12036802.
- ↑ Quetelet LAJ. (1871). Antropométrie ou Mesure des Différences Facultés de l'Homme. Brussels: Musquardt.
- ↑ World Health Organization Technical report series 894: "Obesity: preventing and managing the global epidemic.". Geneva: World Health Organization, 2000. PDF. ISBN 92-4-120894-5.
- ↑ "NICE issues guidance on surgery for morbid obesity". National Institute for Health and Clinical Excellence. 19th July 2002. Retrieved 2007-03-08. Check date values in:
|date=(help) - ↑ "Bariatric Surgery". USC Center for Colorectal and Pelvic Floor Disorders. University of Southern California. 2006. Retrieved 2007-03-08.
- ↑ Romero-Corral A, Montori VM, Somers VK; et al. (2006). "Association of bodyweight with total mortality and with cardiovascular events in coronary artery disease: a systematic review of cohort studies". Lancet. 368 (9536): 666–78. doi:10.1016/S0140-6736(06)69251-9. PMID 16920472.
- ↑ National Institute for Health and Clinical Excellence. Clinical guideline 43: Obesity: the prevention, identification, assessment and management of overweight and obesity in adults and children. London, 2006.
- ↑ Vanhecke TE, Franklin BA, Lillystone MA, Sandberg KR, deJong AT, Krause KR, Chengelis DL, McCullough PA. Caloric expenditure in the morbidly obese using dual energy X-ray absorptiometry. J Clin Densitomet 2006;9:438-444. PMID 17097530.