> BMI is kind of a rough guide to how fat we are. People who are fit
> and regularly working out are exceptions, and should instead use a
> Body Fat Index calculation
Fair enough. But doesn't that make the BMI an inherently useless index for determining whether the country is more athletic or more fat than it was 25 years ago? Because the average BMI rating would go up in both cases. And yet it seems to show up in all these obesity epidemic articles without any mention that theoretically it could just as well be indicating increasing athleticism. (Or, as Chuck pointed it out, an increase in muscle mass that is independent of being in better or worse shape fatwise.)
> But exercise has been down amongst most Americans.
Do you have a good cite on that? My impressionistic data is the opposite. The amount of exercise I do now would have gotten me ridiculed as a health nut 25 years ago, but today is considered pretty minimal. And ditto with my eating habits. 25 years ago they would have been considered prissy, now they are considered downright indulgent.
> The best thing I've read recently about America's obesity problem is Fat
> Land ( http://www.salon.com/books/review/2003/01/09/fat/ ).
I'll take a look at it.
BTW, one last question: are these surveys weighted (so to speak) for age? I would think the average BMI has always gone up with age, and the population is older now.
Michael