I found The Illustrated BMI Categories Project off the New York Times health blog. Basically, in terms of what people intuitively think of as "fat," BMI is a load of bullcrap. Some highlights:
When I started the Weight Watchers deal two months ago or so, I set my goal weight at 160 lbs. The only time I've ever been 160 was before I finished puberty, but that's how skinny I'd need to be to be "normal" according to the BMI calculator I consulted. Now I'm wondering if that's at all feasible, given how arbitrary BMI appears to be. In terms of health, sure, the medical establishment uses BMI as their independent variable, and there are correlations between high BMI and diabetes, heart disease, etc. But other factors, like abdominal fat, seem to correlate better--so why use BMI, given its flaws? Especially given other studies showing that overweight women survive heart attacks *more* often than "normal" women do. Who knows where the health benefits and the risks intersect with regard to BMI? It seems like a mostly confusing and pointless standard.
The New York Times has its own BMI calculator, but it includes other factors like abdominal fat, physical inactivity, smoking, high blood pressure, and so forth. I still get a BMI of 28.7 (fail), but their calculator says that "if you are overweight, but do not have a high waist measurement and have fewer than two risk factors, you may need to prevent further weight gain rather than lose weight." Well, as far as I know, I don't have any other risk factors. Heck, my blood pressure is low. So hmm.
I'm still keeping with the Weight Watchers thing, and trying to exercise more. That's a good idea no matter what. But maybe I don't have to freak out if I never quite drop the 30 lbs...