What is a common limitation of BMI?

A common limitation of Body Mass Index (BMI) is that it does not differentiate between fat and lean mass. This means that BMI relies solely on weight and height measurements to categorize individuals into various weight statuses, such as underweight, normal weight, overweight, or obese. However, it does not provide insight into the composition of that weight. For example, a person may have a high BMI but possess a significant amount of muscle mass, which is healthier than a higher BMI from excess body fat. Therefore, individuals who have a high muscle mass, such as athletes and bodybuilders, may be misclassified in terms of their body fat level simply because BMI does not distinguish between weight that comes from fat versus weight that comes from lean body tissue, including muscle, bones, and organs.

This limitation may lead to misinterpretations of an individual's health status, as BMI alone fails to provide a comprehensive assessment of body composition and associated health risks. While BMI can be useful for population-level assessments, it is less reliable for individual assessments, particularly in those with high levels of physical fitness.