What is BMI?
Body Mass Index (BMI) is a simple index of weight-for-height that is commonly used to classify underweight, overweight, and obesity in adults. It is defined as the weight in kilograms divided by the square of the height in metres ($kg/m^2$).
While BMI is a useful screening tool, it does not directly measure body fat. However, for most people, it provides a fairly reliable indicator of body fatness and health risk levels.