Body mass index

Last revised by Daniel J Bell on 18 Apr 2020

The body mass index (BMI) is a measure of body fat. It is defined as the weight of a subject in kilograms (kg) divided by the square of their height in meters (m) 1. The resultant quantity is measured in kg/m2

A body mass index greater than 25 kg/m2 is the medical definition for being overweight, when greater than 30 kg/m2, then obesity is present.

Limitations of body mass index

The use of the body mass index has clear limitations as a measure of body fat. It does not take into account, the age, gender, skeletal structure, lean body (muscle) mass or distribution of body fat 3. In view of this, the body mass index may give an erroneous impression of an individual's level of body fat.

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