Wednesday, June 23, 2004

You Are Fatter Than You Think

First, an update: I'm still around 125 pounds. For the past three weeks, I've been running more seriously, and am prepping for a marathon in four months. Right now, I'm running about 20 miles a week, a number that will gradually increase in the coming months to a high of about 40 per week.

I'm still eating "on the beach," for the most part, but my portion sizes are such that I haven't continued to lose weight. It is really hard to both engage in hard exercise and diet (ANY diet, not just SBD) at the same time. I imagine I will drop a few more pounds as I approach the marathon, but that isn't a priority for me right now.

Second, a recommendation: _Eat, Drink, and Be Healthy_, by Walter C. Willett. A really good, popular-press book, whose eating recommendations are backed up with reams of evidence--a refreshing change from most "diet" books (and yes, the South Beach Diet is an offender in this department).

Willett says that the standard weight recommendations for Americans are probably too high. We define as "overweight" anyone with a higher body mass index (BMI) than 25. But while the negative health consequences really escalate at BMI > 25, they begin rising at BMIs as low as 22 (which is my own current BMI, by the way). Namely, your risk of gallstones, high blood pressure, and heart disease start creeping up (and in the case of diabetes, start *rocketing* up) even at weight ranges the USDA defines as the lowish side of "healthy." (This makes some sense to me. I am "big boned" and, like a good quality artichoke, heavy for my size. A BMI of 25, the top of the healthy range, puts me at 145 pounds. Only in a funhouse mirror world is 145 pounds on a 5'4" woman, even a large woman like me, a "normal," healthy weight.)

Even more interesting, risk of disease seems to be linear, rather than U-shaped as usually argued. That is, barring your being a smoker or sick with some fatal disease, you really cannot be too rich *or* too thin! Simply put, multiple studies show that the lower your body weight, the longer you live. In the famous Nurses' Health Study, for instance, those with BMIs as low as 17 (for me, a BMI of 17 equals a body weight of 98 pounds!) live slightly longer than those with BMIs between 21 and 25.

Now obviously, I don't think I should weigh 98 pounds. For one thing, I would have to lose not only body fat, but lots of lean tissue to achieve that kind of weight. For me, a BMI of 17 genuinely wouldn't be as healthy as, say, a more muscular BMI of 20 (116 pounds). For another, such a weight would be so difficult to achieve and maintain that I would be utterly miserable (as well as stick-man fugly). But the point is: as our waistlines have expanded, so seemingly have the recommendations for "healthy" weight. This may in part be because the good folk at the USDA don't want to make people desperate and give up. And hey, maybe they're right. After all, if I were truly obese (as more and more Americans are), I'd certainly be better off even at a still-chunky 145 pounds.