Why BMI is Not a Lie (but it's Tainted by History)

BMI is an entry level health marker with a troubled past, rooted in eugenics. The history is not great. Read more here: https://www.henryford.com/blog/2023/11/how-bmi-is-flawed-and-race-gender-and-age-based

Does this discount it as an entry point into assessing an individual's health and fitness? It definitely casts shade in its use and made me rethink my use of it in general. I will keep updating this post as I learn more.

As someone who occasionally uses BMI as one of many tools to look at how someone is improving, I give it as much credence as the scale - it's one simple marker that doesn't tell the whole story, but can give you a quick snapshot of current data.

According to BMI sclaes, despite having a low body fat you can still be “overweight” and put your body through increased stress. BMI is a description of health outcomes based on weight divided by height squared. When very fit but overweight people hear the term overweight or obese, they immediately pinch their midsection and complain that “this doesn’t apply to me.” 

But it does. 

Research has shown a J-shaped association between mortality risk and BMI, meaning being both under and overweight can be problematic as it relates to all cause mortality. The sweet spot of this J-curve lands on the higher end of 'healthy' ranges, right around 25, technically considered on the border of overweight.

People above the normal BMI (18.5-25) have a 51% increase in mortality over those in the healthy range. BMI is not saying that those with extra body fat in the overweight and obese category alone are at a greater risk of all cause mortality. 

Simply weighing more (despite being lean) is less healthy as it relates to all cause mortality. 

There is no specific boogeyman coming for you, but an increased combination of risk from heart disease, high blood pressure, high blood triglycerides, multiple cancers and on and on. 

BMI is also not a measure of health. You could be sitting pretty at a BMI of 24 and be completely unhealthy. Lack of exercise, smoking, drinking, lack of sleep can all compound and greatly increase your risk of all cause mortality. Likewise, you could have a BMI of 26 and have the cleanest blood panel the world has ever seen. 

The most common error with BMI is conflating a high BMI with high body fat. The lean body builder claims to be exempt from the statistics because they have 5% body fat and 240 lbs of lean muscle on a 5’8” frame. Even the bodybuilder will admit it took years of over eating, and perhaps anabolic steroids to get that big. 

“During my career, my off-season calories increased over the years. In the early days it was roughly 3,500 - 4000 calories and over the years as I got bigger, it eventually increased to 7000” said 6 time Mr. Olympia Dorian Yates. I think it’s general knowledge that these are not healthy or sustainable inputs. Yates was eating for two or more humans at this point, and by his own admission was using steroids regularly. 

Common sense tells us gorging yourself, manipulating your hormone levels through food and eventually chemicals is not good for you. The experts agree; bodybuilders, particularly professionals, face a significantly higher mortality risk—roughly 34% higher than the general male population—with a, often, premature mean age of death around 45–47 years. 

BMI is blind to actual body fat. There is no asterisk next to a BMI of 29 that says “...but if you’re lean, you are exempt from the statistics.” Use common sense and understand the facts about BMI and what it means to you, and then apply this to your own life. 

For me, personally, when I’m on the high end of the ‘normal’ 18-25 BMI scale, I feel best and move well. I’ve been told that I look ‘too lean’ at that weight, but it feels good, and at the end of the day vanity dies and you (hopefully) continue to live on.

If I’m pushing toward a BMI of 27, I feel slower and less agile. The highest I’ve gotten is 30. I was the strongest I’ve ever been, but also the slowest and my cardio was not great. I chose to lower it and feel better having done so. 

Set your own BMI (or don't) accordingly & sound off in the comments!