Body Mass Index (BMI) dates back to before the civil war. It was created by a man named Adolphe Quetelet. It was originally called the Quetelet Index, until it was later named BMI in 1972 by Ancel Keys. BMI is used to determine if a person is underweight, healthy, overweight, or obese. It isn’t very difficult to calculate a BMI. It can be found by dividing a person’s weight in kilograms by their height in meters squared. This is a big reason why it is so widely used. Anyone can calculate their own BMI after a couple measurements.
What can be wrong with it then? Actually, there are a couple things wrong with it. One of the biggest issues with BMI is that it doesn’t account for muscle in people. Athletes tend to have high BMI’s because they are usually very muscular, which causes them to weigh a lot more. An athlete that is muscular and has a high BMI obviously isn’t obese. NFL running back Adrian Peterson is listed at 6’1″ tall and weighs 220lbs. At that stature, his BMI would be about 29, which is considered overweight and on the brink of obesity. This is obviously a flaw with BMI. On the left side is a picture of him, and I don’t think many people would think he is overweight or anywhere near obese.
A similar problem is that if a man and woman both have the same BMI, odds are that the woman will have more body fat than the man. This is just because of the way the 2 genders are. Older people tend to have more body fat than younger people too.
BMI also has an issue as a whole. It isn’t so much the way you calculate it, but the issue is what it is used for. BMI was originally meant to be used for a group of people such as a population. Obviously, there are still flaws in that, because it still doesn’t account for muscle mass, age, or gender as previously stated. Now it has transitioned into being used on an individual basis where it doesn’t work as well. Although, a population’s BMI might not be 100% correct either it could lead someone in the right direction.
Why do people still use BMI then, if it is so obviously flawed? It is still used all the time because of its simplicity and the lack of alternative methods. There are alternative methods to BMI, but they are usually costly or not practical. As fallacious as BMI seems it is said to be correct about 80% of the time. This is a very good percentage for something so easy to calculate. BMI is an even better predictor when it comes to the extremes. If someone has a very low BMI, the odds are that they will be skinny.
Although not perfect, BMI is still a valuable tool for people to use. It shouldn’t be seen as law, but it can be used in a lot of instances. It still works for populations since that is what is was originally created for. Someone who is educated on BMI can productively use it.
You can check your BMI without doing any math or without any knowledge of the metric system.