Body Mass Index (BMI) is a numerical measure used to assess an individual's body composition in relation to their height and weight. It provides a general indication of whether a person's weight falls within a healthy range, is underweight, overweight, or obese. While BMI is widely used due to its simplicity and accessibility, it has some limitations. It does not directly measure body fat or distribution of fat, muscle mass, bone density, and other factors influencing weight and health. As a result, it may not accurately reflect an individual's overall health status, particularly in athletes, older adults, and those with higher muscle mass.

BMI is calculated by dividing an individual's weight in kilograms by the square of their height in meters (BMI = weight (kg) / height (m)^2).