Is Fat Really Fit?

The body police can be so militant and appearance-fixated that studies reversing the conventional link between illness and being overweight are seductive.

That doesn't mean they're true, however. Scientific American breaks down a prominent CDC finding that slightly overweight adults have lower mortality rates than the slender:

Stampfer cites the Flegal study as a prime example of the errors the critics make. The reason being overweight seemed to reduce mortality is because Flegal used the wrong comparison group, he says. The lean group in her study included smokers and people with chronic illnesses—both of whom have increased mortality risks, but not because they are slim. “When you get sick, you lose weight, and you die,” Stampfer says. Compared with those who are smokers or chronically ill, people who are overweight come out looking better than they should.

Willett points to a November 2006 study by James A. Greenberg, a researcher at Brooklyn College, to prove his point. Greenberg performed a similar statistical analysis to Flegal’s, this time adjusting for factors such as a history of serious illness. When he did, the number of extra deaths for the obese—compared to those with a “healthy”
weight—tripled. And he found a significant increased mortality risk in those who were merely overweight, contrary to Flegal’s finding that being overweight lowered the risk of death.

Katherine Flegal insists that her data later withstood such adjustments, but the fact remains that the large majority of such studies do find that being overweight is bad for your health. It's not a fun message when delivered by people who seem able to eat anything without repercussion, or spend their evenings toiling like in gyms like so many lab rats, but they're right.

Can Fat Be Fit? [Scientific American]
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Image: HeatedGroundPhotography*