"Learning": What is BMI (Body Mass Index)?

Body mass index (BMI) is a simple index of weight-for-height that is commonly used to classify overweight and obesity in adults. It is defined as a person's weight in kilograms divided by the square of his height in meters (kg/m²).

 

For adults, WHO defines overweight and obesity as follows:

• overweight is a BMI greater than or equal to 25; and
• obesity is a BMI greater than or equal to 30.

BMI provides the most useful population-level measure of overweight and obesity as it is the same for both sexes and for all ages of adults. However, it should be considered a rough guide because it may not correspond to the same degree of fatness in different individuals.

For adults over 65, the BMI classification can sometimes be inaccurate.

For children and adolescents (up to 18 years old), it is recommended to use BMI curves which take into account BMI, sex and age.