Body mass index (BMI) | definition of body mass index (BMI) by Medical dictionary
body mass index (BMI)
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body mass index (BMI) body mass in kg divided by height in metres squared (kg.m-2) used to evaluate the extent of adiposity. The WHO classification for BMI is: less than 18.5, underweight; 18.5-24.9, normal weight; 25-29.9, pre-obese; 30-34.9, obese class I; 35-39.9, obese class II; greater than 40, obese class III. These predicted values cannot be used in children, pregnant women and certain other adult subjects. Also a high BMI can lead to an overestimation of fatness in relatively lean individuals with a disproportionately high muscle mass because of genetic make-up or exercise training; this applies, for example, to body builders, weightlifters or upper weight class wrestlers. See also obesity.