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Obesity is a medical condition in which excess body fat has accumulated to the extent that it has an adverse effect on health.〔WHO 2000 p. 6〕 Relative weight and body mass index (BMI) are nearly identical and are reasonable estimates of body fatness as measured by percentage body fat. 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.〔WHO 2000, p. 7〕〔NHLBI p.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.〔(Normal Weight Obesity: An Emerging Risk Factor for Heart and Metabolic Problems ). Mayo Clinic. March 27, 2008.〕〔Katherine Zeratsky, R.D., L.D.. (Normal weight obesity: A hidden health risk? ): Can you be considered obese if you have a normal body weight? Mayo Clinic - Obesity Expert Answers. Aug. 5, 2009. Retrieved 2010-1-25.〕 ==BMI== (詳細はBelgian statistician and anthropometrist Adolphe Quetelet. BMI is an accurate reflection of body fat percentage in the majority of the adult population. It however is less accurate in people such as body builders and pregnant women.〔NHLBI p.60〕 A formula combining BMI, age, and gender can be used to estimate a person's body fat percentage to an accuracy of 4%.〔Seidell 2005 p.3〕 An alternative method, body volume index (BVI), is being developed in an effort to better take into account different body shapes.〔Romero-Corral, A. Somers, V. Lopez-Jimenez, F. Korenfeld, Y. Palin, S. Boelaert, K. Boarin, S. Sierra-Johnson, J. Rahim, A. (2008) 3-D Body Scanner, Body Volume Index: A Novel, Reproducible and Automated Anthropometric Tool Associated with Cardiometabolic Biomarkers ''Obesity A Research Journal'' 16 (1) 266-P〕 BMI is calculated by dividing the subject's mass by the square of his or her height, typically expressed either in metric or US "Customary" units: :Metric: :US/Customary and imperial: 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.〔WHO 2000 p.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. *Any BMI ≥ 35 or 40 is ''severe obesity'' *A BMI of ≥ 35 or 40–44.9 or 49.9 is ''morbid obesity'' *A BMI of ≥ 45 or 50 is ''super obese'' As Asian populations develop negative health consequences at a lower BMI than Caucasians, some nations have redefined obesity. The Japanese have defined obesity as any BMI greater than 25 while China uses a BMI of greater than 28. 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. However, their mean body fat percentage, 14%, is well within what's considered a healthy range. The preferred obesity metric in scholarly circles is the body fat percentage (BF%) - 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%. Levels in excess of 32% for women and 25% for men are generally considered to indicate obesity. 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. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Classification of obesity」の詳細全文を読む スポンサード リンク
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