The most widely used measurement for obesity. The BMI approximates body mass using a mathematical ratio of weight and height [(weight in kg ÷ height in meters2) or (weight in pounds ÷ height in inches2 x 703)].
A BMI of 30 or more is regarded by most health agencies as the threshold for obesity. A BMI of 40 or more generally qualifies as morbid obesity. However, note that BMI measurements in body-builders and athletes may not be accurate determinants of obesity because the BMI does not distinguish between muscle and fat.
Generally, this term refers to what a person of a given height and body frame should weigh. In other words, the desired weight for optimal health and fitness. There are several problems, however with current calculations of ideal weight: a) body fat percentage of distribution is not accounted for; b) only some tables account for different body frames or ages; and c) most importantly, there is no consensus about which formula or table to use.
While the topic remains subjective, there are two primary sources for determination of ideal weights: the Metropolitan Life Height and Weight Table, and The World Health Organization Classification of Adults According to BMI. The WHO classifies “the normal range” of BMI as 18.50-24.99, and “overweight” as >=25.002.
In a clinical study of Lap-Band in people with a BMI of 35 or above, the Metropolitan Life Table was used to determine ideal weight. In a separate clinical study of Lap-Band in people with a BMI between 30 and 40, the WHO definition of 25 BMI was used as ideal weight.