Ten years ago, the AARP surveyed more than half a million members about their weight, height and medical histories. The point was to study the relationship between body mass index, or BMI, and the risk of early death. The results of the study were published Tuesday in the New England Journal of Medicine.
At the time the surveys were mailed out, physician Tim Byers says that the concern about weight-related mortality seemed very remote, especially to people who consider themselves just a few pounds overweight.
But as researchers followed the AARP volunteers and tracked who died, they began to see that just 15 or 20 pounds of extra weight can have a significant effect.
"What this study shows is that even at body mass indexes of 26, 27, 28 -- levels of just a little bit of body fat -- mortality risk does begin to climb up," Byers says.
And it doesn't take much weight gain to put you in the danger zone.
Byers, who's now a professor of preventive medicine at the University of Colorado, is 5 feet 10 inches and weighs 192 pounds, putting his BMI at about 27.5. Typical of middle-aged men, Byers carries the extra weight around his middle, so he appears to be normal weight in most of his clothing. He says that for years, he was not concerned about the extra weight because he didn't have high blood pressure or high cholesterol.
"One of the hopes I'd had personally," Byers says, "[is] maybe body fat is not a risk factor. But I'm realizing it is. There are adverse consequences of carrying extra fat, apart from blood pressure and serum cholesterol levels."
For now, the finding that being moderately overweight increases one's risk of premature death is just a theory.
Martin Binks, an obesity expert at Duke University, says that a significant shortcoming in this particular study is that researchers had to rely on self reports of weight and height from the AARP volunteers. And the researchers did not validate that they were accurate.
"With overweight individuals ... you're more likely to see an underreporting of weight," Binks says. "So they're likely to recall themselves being lighter than they are."
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