BMI Says I'm Obese. Here's Why That Number Is Garbage

Why BMI Calls Me Obese at 235 Pounds

The cheapest health assessment you will ever run costs nothing and takes ten seconds. Get naked and stand in front of the fucking mirror.

If you were to look at every modern BMI index measurement tool that does that calculation it would tell you that I'm obese, seriously obese, the kind of number that makes a doctor raise an eyebrow before you open your mouth. I think based upon like the military's expectation of how heavy I should be for my height it's like my max at 38 years old would be like 189 pounds or something, and I'm 235.

So either I am carrying 46 pounds of health risk, or the number is measuring something it was never built to measure.

BMI divides your weight by your height squared, and that division is the whole calculation. It does not know whether a pound is muscle, fat, bone, or the water sitting in your muscle after a heavy training week, so it treats all of them the same and hands you one score.

The formula came from a Belgian mathematician in the 1830s who was trying to describe the average characteristics of a population, not diagnose a person. Across thousands of people at once, individual variation washes out and it works fine.

Pull one person out of that population and it falls apart. A lean man carrying 190 pounds of muscle at 5'10" and a sedentary man carrying 190 pounds mostly as fat at 5'10" get the identical BMI, identical category, identical risk label.

Which is why people reach for something more precise and land in a different trap. They want to like pay all this money for these DEXA scans and fucking go and what's my body fat percentage.

DEXA is more accurate than BMI because it separates lean mass from fat mass. But accuracy and usefulness are two different things, and knowing your body fat is 14.2 percent instead of 16.8 percent tells you nothing about whether your cardiovascular system, your hormones, or your recovery are working.

Body composition sits downstream of everything else. It is a byproduct of how you train, sleep, eat, and recover, so by the time it shifts you are seeing the trailing edge of changes that started weeks or months earlier.

The markers sitting upstream move faster and tell you more.

The way that you should be measuring your health is how do you feel? How do you sleep? For men do you wake up with the fucking morning wood? Can you perform well? Do you feel strong? How's the quality of your sleep? What's your blood pressure? What's your resting heart rate? What's your VO2 max? Nobody cares what your body fat percentage is.

The morning erection one is worth sitting with, because the signal has nothing to do with vanity. It requires functioning endothelium, meaning the lining of your blood vessels responds properly to nitric oxide, and it requires adequate testosterone, and it requires your parasympathetic nervous system to actually be running during sleep instead of your body sitting in stress mode all night.

Three systems have to be working for that to happen. When it stops happening, it usually stops before anything shows up on a blood panel.

Resting heart rate follows the same logic. A rise of five or ten beats over your normal baseline, held for a few days, means your nervous system is under load, and that shows up long before your weight does.

VO2 max is the one I would track if I could only track one, because it reflects how well your heart, lungs, and muscles move and use oxygen together.

Start with the mirror and how you feel when you wake up. If those are off, look at blood pressure and resting heart rate before you pay anyone for a scan.

I promise you're the only one who cares about your body fat percentage. Everyone else is reading your energy, your posture, and whether you can keep up.