Body Mass Index (BMI) is a convenient approximation used to broadly categorise an individual as underweight, normal weight, overweight, or obese based on their weight and height. BMI is calculated by dividing an individual’s weight in kilograms by the square of their height in meters. While BMI is a convenient tool to use at a population level to assess overweight and obesity, it doesn’t necessarily reflect body fat distribution or describe the amount of body fat in different individuals. Athletes with high bone density and well-developed muscles may be overweight but have low body fat. Likewise, inactive individuals may appear to have an acceptable BMI when, in fact, they may have too much body fat and low muscle mass.