The Troubles with BMI


The Troubles with BMI

Body Mass Index, or BMI, is one of those things that’s easy to look up to see if we’re considered “healthy”. The issue with how the BMI is measured is that it fails to take a lot of things into consideration. Just for reference, the formula used to calculate BMI is simply your weight, in kilograms (2.2046lbs per kg for reference), divided by your height squared, and that’s it. There’s taking into account activity level, or body composition between lean tissue and fat. This can lead to a problem with having either a good or bad Body Mass Index score.

Firstly I’ll use myself as an example. I’m 5’10” and weigh about 180 pounds, which gives me a BMI score of 26. This is categorized as “Overweight” according to how it breakdown. It doesn’t take into account my pretty high activity of several days of CrossFit and aerobic work a week, or that I have body fat composition of under 10 percent. That, combined with having a resting heart around 50 and a blood pressure close to 110 over 60, makes me pretty confident in saying that I’m quite healthy. To go even further I think I could gain another 10 or even 15 pounds to put me closer to the “obese” measure of the BMI index and still be healthy.

Clearly there’s discrepancies on the side of it saying your unhealthy while you’re clearly not due to other factors, but it’s being inaccurate in the other direction that could actually be worse. There’s every bit the chance that someone could read as perfectly healthy on the BMI, but have more similarities internally to someone who’s close to obese than a true healthy person. Most of us all have that person we know who never works out, just eats junk food all the time, and still stays super skinny. A guy that’s 6′ and weighs 160 is considered perfectly healthy on the BMI, but depending on their lifestyle habits they could easily have a body fat composition pushing 30%. This would put them in at extremely high risks for heart disease, high blood pressure, and diabetes, even though they wouldn’t resemble what we think of as a diabetic.

The body mass index was made up in the early 1800’s, so it’s kind of simply outdated. As a general reference point it could be helpful to pay attention too, but make sure to use other markers to make it a little more concrete. You may have a high BMI, but if you’re active, feel good, and have clean blood work then I wouldn’t stress about it. On the other end just cause your BMI reads healthy at a glance doesn’t necessarily mean you’re all good, and some more specific check ups might be smart to be safe.

-Coach Tristan