BMI: What It Is and Why It’s Wrong

Created in the 19th century, the Body Mass Index has, in the last 50 years or so, become a standard go-to for determining one’s physical health and well-being. The BMI, or Body Mass Index, is a measure of the body’s weight divided by the square of the body’s height, if this sounds confusing, it really isn’t. BMI is easy to calculate and does not require fancy equipment or state-of-the-art technology.

Since the 1980s, the World Health Organization has used the BMI to measure obesity levels and publish statistics on the average relative health and weight of the populations in different countries. However, despite its ease of use and universal applicability, the BMI has come under fire recently for a number of reasons.

1. BMI doesn’t distinguish muscle from fat

Muscle is denser than fat by a good amount and therefore will weigh more. The BMI formula fails to make a distinction between fat mass and muscle mass. What does this mean for The Rock, the toned and muscular professional wrestler? It means that according to his BMI, he is obese! Without separating fat and muscle, athletes usually find themselves on the overweight or obese end of the BMI spectrum when in fact their bodies are in top physical condition and have a very low boy fat percentage! A person with strong bones, good muscle tone and low fat will have a high BMI – are they obese? Probably not. Athletes typically indulge rarely in fatty foods and have high protein diets (which may be supplemented with protein powders, pre work out shakes and top quality work out supplements) – these bodies are physically fit and strong.

2. BMI does not actually measure the percentage of body fat

The BMI formula does not take into consideration the percent of body fat. This crucially important metric is completed left out of BMI measurements, thereby failing to include one of the most distinguishing factors about a person’s actual health.

3. BMI does not take into account frame size, or bone and cartilage mass

Bone is far denser than muscle and is twice as dense as fat so it is necessary to take into account the person’s relative frame size and bone mass in order to accurately dictate whether or not they are within a healthy weight range. The BMI fails to do this and instead lumps all weight together.

4. It’s one size fits all

The BMI does not account for very different body types and myriad other factors that can contribute to a body’s weight. For example, consider the very different body types of Samoans or Thais – the BMI does not take this into account. Nor does it factor in other health measurements or water weight. The BMI simply presents one equation which is supposed to work for everyone, from muscular, athletic men to slender, young women.

What we take away from recent studies into health and obesity in the United States is that appearances can be deceiving and that the BMI may not be the most reliable way to gauge obesity levels in our nation. After all, a slender person may have a low BMI but without working out and eating well they may still have a high percentage of fat which can cause serious health problems. The course of action to ensure health at any weight is to work outregularly, eat well, get plenty of rest, and drink loads of water!