Comment by MostlyStable
1 day ago
At a population level, it's great. For individuals, it can fail in all kinds of ways. For me: it is not very good because my body has very strange proportions. I'm 6'2", but my waist is barely higher than my 5'1" wife, and my torso is nearly the same length as my 6'7" brother.
In other words, for my height, I have a very long torso and very short legs. I think it should be relatively obvious that an inch of leg weighs significantly less than an inch of torso, so at a given level of body fat percentage, I'm going to weigh quite a bit more than someone my same height with more typical proportions, and thus my BMI reads me as more overweight than it otherwise would.
My point is not that BMI is bad or useless or anything else. My point is that it was designed as a population statistic and that it can be fraught when one tries to apply it to any individual with no nuance. A high BMI should cause one to consider and examine your health and weight. But it should not over-ride specific details about your physiology that point in the other direction.
It's actually still useful. It doesn't function as well as a measure of fatness for you as an individual, but that was only ever a proxy anyway.
It still functions well as a measure of load on your circulatory system, joints, you name it.
Your body is working harder than a typical 6'2" person, even if you have a great waist-to-hip ratio.
(But you'd still be better off with a smaller WTH ratio!)
Do you have a concrete example, though? Like an actual body fat percentage measurement that conflicts with what BMI explains for you?
I was also in the "overweight" category at one point while being low body fat. It was never a problem for anything, anywhere. I wasn't going to doctors who looked only at the BMI sheet and then told me to lose weight, because everyone could see that I was not overweight.
Body fat percentage can't conflict with BMI because BMI is not an estimate of body fat percentage.
And I agree that it's never caused me problems, but that's because I and, as you suggest, doctors who look at the number, have understood that it's not that big of a problem in my case. That's what I mean by not looking at the BMI number naively and ignoring other physiological states.
I don't think anything you said conflicts with anything I said, and it sounds like we mostly agree.
The serious backwoods rock climbing cohort calls that "goon coefficient". I (also) have a high goon coefficient.