Body mass index is a value that allows you to assess the degree of correspondence between a persons weight and his height and thereby, indirectly, assess whether the weight is insufficient, normal, overweight (obesity)It allows you to assess the degree of correspondence between the mass of a person and his height. The resulting digital value shows whether your weight is within normal limits or there are deviations in one direction or another.This gives you an idea of whether you are "underweight", "normal weight", "overweight" or "obese" based on your height. BMI is one of the tools that help healthcare providers assess the risk of chronic disease.