BMI is a calculation that is very well suited to assessing the levels of overweight and obesity in large populations. It adjusts for weight and height which allows people of very different body weights and heights to be grouped together into BMI ranges.

It is calculated by: BMI = weight(kg) ⁄ height(m)²

BMI calculations should be used with caution when looking at the health risk of an individual person because BMI calculations will:

• Overestimate the amount of body fat for people with proportionally high muscle mass e.g.athletes and people of certain ethnicity

• Often underestimate the amount of body fat for the elderly & people with a physical disability who may have muscle wasting.

Classification of weight by BMI