General Discussion
In reply to the discussion: I used to be fat [View all]MillennialDem
(2,367 posts)Well, it is flawed because of people with significant muscle and people with particularly larger frames - that is indeed true, but it is ALSO FLAWED because of how it accounts for height!
BMI squares weight as you increase in height. So someone twice as tall as you would "only" weight four times as much as you. They would obviously double your weight because they are twice as long as you. They should also be twice as wide (distance from right shoulder to left shoulder, or right hip to left hip in a straight line) so 2x2 = 4 times as heavy as you. But wait! People are three dimensional, not two! So they should also be twice as deep as you (belly to back distance in a straight line, or face to back to head distance in a straight line).
So twice for height, twice for width, and twice for depth. 2x2x2 = 8!
It is nonsensical that BMI squares weight as height goes up. I've heard some people argue that taller people are not exactly proportional to shorter people, but it still does not mean square for the exponent is accurate. Maybe 2.5 or 2.6.
In fact studies seem to correlate being taller with being more overweight (by BMI standards), but I think the eye calculator shows the opposite (tall people are generally "thinner", of course there are fat tall people and thin short people, but on average...)