– Why do doctors care so much about your BMI when it’s has been proven to be such a flawed metric for ones actual health?
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BMI is just a formula of weight divided by height, times a constant. Your body weight is equal to the weight of your guts, plus the weight of your bones, plus the weight of your muscles, plus the weight of your fat. For people of similar heights, their guts and bones probably weigh around the same amount, so the difference comes down to muscle and fat.
If you’re an athlete, you have a bunch of muscle, which is dense (it weighs a lot), so your body weight will be higher than someone who doesn’t have muscle or fat. So their BMI will be very high, even though they are extremely healthy. However, 95% of adults are not athletes. If you have two people who are the same height and are about equally active, the one who weighs more is likely going to have more fat on them, and will be less healthy.
So BMI is a quick and convenient way to sort “average” people into buckets that should correlate with their general health. Actually measuring body fat % directly is a difficult and imprecise science, and it doesn’t really matter for almost the entire population.
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