The 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/her height in meters (kg/m2). However, it should be considered only an indicative guideline, because it may not correspond to the same degree of overweight and obesity in different individuals. However, the respective public health burdens of overweight and undernourishment/micronutrient deficiencies are not quantified only in terms of the number of people affected.