Why BMI is a flawed measure of your fitness

What is BMI?

Body mass index (BMI) is a 200-year-old formula developed to measure the degree of obesity in the general population. But it isn’t the best way to measure your health.

BMI is calculated from the mass (weight) and height of a person. It is defined as the body mass divided by the square of the body height.

The BMI categories are defined by the World Health Organization as underweight, normal weight, overweight, moderately obese, severely obese and very severely obese.

BMI was introduced in the early 19th century by Belgian Lambert Adolphe Jacques Quetelet. He was a mathematician, not a physician.

BMI value doesn’t tell us the overall body composition. It fails to tell us the percentage of fat, muscle, bone, water and tissue that our body consists of. Two people of the same weight and height could have very different body compositions.

Many athletes fall in the obese category of BMI because of high muscle mass. But that doesn’t mean they are unhealthy or fat.

Higher muscle mass is beneficial as it helps to burn more calories even when resting. It increases your strength and movement. But BMI gives a flawed image of being unhealthy if your weight doesn’t fall in its “normal” range.

A person can be in a “normal” weight range according to the BMI but practice a sedentary lifestyle. People who don’t get enough exercise can have health issues like heart disease, diabetes, and high cholesterol.

Body composition is a better indicator than BMI as to whether your body fat percentage is in a healthy range.

Final Note: Be wary of only using BMI as a measure of your health, and focus instead on body composition. MRI, hydrostatic weighing, DEXA, calipers, waist-to-hip ratio, blood pressure, and glucose levels are better ways to understand whether you are healthy or not.