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Can You Be Fat and Fit and Beat Obesity-Related Mortality?
February 14, 2003
Maia Szalavitz
The New Republic's contrarian stance on the perils of being overweight

The recent news on America's weight problem has been relentlessly bad: We're getting fatter, our genes are designed to push us to overeat, and 300,000 people are estimated to die each year of "fat-related" causes - more than die from alcoholism and creeping up on the number for smoking (400,000). National statistics say that 65% of Americans are overweight of whom 31% are obese.

But wait, says The New Republic, it's not being overweight that's killing us, it's lack of exercise and yo-yo dieting.

Writer Paul Campos claims that people who are both fit and fat do not have the 200% or greater increased risk of mortality the large studies find linked to obesity. In fact, he says, people on the low end of the body-mass curve are just as likely to die as those on the high end.

However, the contention that being thin is equally as unhealthy as being fat is suspect. While early studies inflated the risks related to being thin because they included smokers (who are likely to be thin given that nicotine is an appetite suppressant) and sick people (who often waste away before death), some studies still found excess risk when they excluded such groups. Now, though, even that smaller remaining risk is questionable, at least amongst younger people (in the very old, extra fat may help survival since wasting takes longer and this time may allow the body a better chance to fight off a disease).

Studies of animals have found increasing evidence that those put on restricted calorie diets (about 30% less than normal) live far longer than others of their species - 40 percent longer, in fact. Primate studies have not yet been completed, but so far they look like they support the rodent, dog and fly work.

In humans, biomarkers (such as insulin levels and body temperatures) associated with calorie restriction in animals are good predictors of mortality rates. Further, researchers found that a mutation in a single gene related to food metabolism doubled the lifespan of flies. The related protein in yeast, called Sir2, doubled lifespan and researchers said it is an "attractive" target for a drug.

Research also increasingly shows that high calorie intake may increase the level of free radicals, which are reactive compounds that can attack organs and tissues and reduce, over time, their ability to function properly. Free radicals can also cause cancer. So, sadly for those of us who aren't supermodels, we may not be able to criticize the too-thin (short of anorexia) on health grounds.

The New Republic story nonetheless emphasizes that it is fitness, not fatness, that determines health. Thin, sedentary people, Campos claims, have equally high mortality rates as fat, active people. Yet the fitness and fatness are inextricably correlated: thin people don't tend to be sedentary and fat people don't tend to be active. Studies have consistently linked higher rates of activity with lower rates of obesity; in fact, Campos' article even mentions that 80% of Americans don't even get a half hour of moderate exercise a day.

So, while fat may just be a symptom of a sedentary lifestyle in which more food is consumed than used to meet energy needs, solving both problems requires the same solution. Though Campos argues that the diet industry puts too much emphasis on weight loss, most people know in their hearts that the only way to really keep pounds off and become healthy is boringly familiar: Eat better and less, move more.

If you genuinely do that consistently, you'll get fit - but you also probably won't stay fat. Otherwise, you'll have to wait for the Sir2 drugs.



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