Kirk wrote: For individuals, certainly. Averaged across the entire population its not a bad measure.
Yeah, I don't think America actually got more athletic over that time frame.
I should also clarify my views on BMI.
It's blatherskite the way some insurance companies or others use it as a diagnostic tool. It's a starting point. If you've got a BMI in the "overweight" category it's a reason to examine your overall health or for a doctor to ask questions.
On the other hand, if your BMI is in the "obese" categories, you almost certainly have issues that will affect your health. Remember - Arnold's competition weight put him at 30.2 BMI, barely into "obese." And he sure wasn't natural.