So many commenters forget that BMI was created based on statistical analysis of young white men - specifically, soldiers. Just like IQ tests. So neither accounts for age, height, race, sex, disability, financial background, illness, mental health, limb differences, etc and so on. BMI is only useful for evaluating if your average young white man is fit for military service, and that's it. But because it's such a nice number with a simple formula, it got slapped on everything. Which is shit.