The Pros & Cons of BMI

It usually goes one of two ways …

Either your doctor adheres strictly to the principle of BMI and you find yourself in a never-ending tug-of-war or you’ve already decided to give up on BMI altogether, writing it off as a relic of days gone by.

The reality is that the answer is a bit more nuanced.

We have this conversation probably once a quarter in the gym and our answer is always the same. There is room for interpretation, for discussion.

See, BMI is really just a measurement of the relationship between your height and weight.

Since weight doesn’t exactly correspond linearly with height, you’ll find that your shortest friends and tallest comrades have a more difficult time relating to the BMI chart.

Moreover, BMI is just a singular measure of health and should come as a component of a much larger panel of health markers.

But is BMI necessarily wrong? Not entirely.

The first thing we hear often is that BMI doesn’t account for the fact that humans are bigger now than they used to be (see: old doorways in Boston or New York). While this is true, it’s mostly true of height (not weight).

Don’t fall for this one. BMI still accounts for increasing height.

The second thing we hear often is that BMI doesn’t account for muscle mass. This is true (to a point). Someone who’s invested in strength training may carry a considerable amount of lean mass compared to their non-exercising counterpart.

And what’s more, somebody who weighs less but carries significantly less lean mass isn’t necessarily healthier.

However, don’t be tricked into thinking that the BMI chart is wrong because the you met an NFL running back once and he was 5’6″ 220 lbs.

Having an excessive amount of muscle on your body (regardless of your aerobic capacity or athleticism) is still hard on your organs.

Plus, it usually requires performance-enhancing drugs and those are unequivocally not healthy.

So, no, the BMI chart is not perfect. “All models are wrong, but some are useful.”

The BMI chart is certainly still useful.