It's pretty shocking how little food the human body actually needs and how little weight you actually need to carry, and anything over that is just stressing the circulatory and muscle systems. (And providing more cells from which cancer can potentially start, and more energy to feed it if it does.)
Losing 40 pounds on my frame… I’d look like death. I think BMI as estimated by the simple formula is a useful guide for the median height and build person, but it’s used as a health designation whose meaning is frankly bunk. I lay higher insurance rates, for example because of supposed risk of diabetes.
My wife was even worse. She had big boobs, so was declared obese. She was a runner, cyclist, and was a competitive swimmer, but was labeled a fat girl by her doctor.
Stupid things like this turn people off from medicine and delay being treated for real problems.
It’s not the most accurate thing, but it’s close enough for most people.