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This is ALL THINGS CONSIDERED from NPR News. I'm Robert Siegel.
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There is new evidence today about the hazards of just being moderately overweight. A study published in the New England Journal of Medicine lays out just how much middle aged body mass it takes to increase the risk of early death.
NPR's Allison Aubrey reports.
ALLISON AUBREY reporting:
Ten years ago the AARP, formerly known as the American Association of Retired Persons, surveyed more than a half million members. They asked people to tell them their weight, height and whether they ever smoked. The point was to study the relationship between body mass index, BMI, and the risk of early death.
Physician Tim Byers says back then the concern over weight related mortality seemed very remote, especially to people who consider themselves just a few pounds overweight.
Dr. TIM BYERS (Physician): We think of overweight as being clearly fat. People who look fat in the face, the neck and the arms and so forth.
AUBREY: That sort of recognizable obesity is clearly associated with an increased risk of early death. But as researchers followed the AARP volunteers and tracked who died they began to see that way before people began to look obese, they're at risk.
Dr. BYERS: What this study shows is that even at body mass indexes of 26, 27, 28, levels of just a little bit of extra body fat, mortality risks does begin to climb up.
AUBREY: So what kind of weight gain does it take to reach a BMI of 27 or 28? Byers, who is know a professor of Preventive Medicine at University of Colorado, uses himself as an example. He's five foot ten, weighs 192 pounds and his BMI is 27.3. He says like a lot of middle aged men he carries a little extra weight around his middle, but in most clothing he doesn't look overweight. So for years he says he was not concerned.
Dr. BYERS: One of the hopes that I had had personally was that well, since I don't have high blood pressure and since my cholesterol wasn't high, maybe my body fat was not really a risk factor. What I'm beginning to realize is that it is. There appear to be adverse consequences of carrying extra body fat apart from just blood pressure and serum cholesterol levels.
AUBREY: To get his weight under control, Byers says he's making changes in his diet and getting more exercise. He says all this might help reduce inflammation, which is one theory as to why weight gain may increase the risk of early death.
Dr. BYERS: It looks now like inflammation may be an important factor in both heart disease and cancer, and so it could be this high inflammatory state caused by extra body fat that is very important in the risk of mortality.
AUBREY: For now this remains theory, as does the overall finding that being moderately overweight increases one's risk of premature death. Martin Binks is an obesity expert at Duke University. He says one single study can never settle a controversial question and he says this study has a significant shortcoming. Researchers had to rely on self reports of weight and height from the AARP volunteers. Nobody independently confirmed those numbers.
Mr. MARTIN BINKS (Duke University): With overweight individuals you are more likely to see an underreporting of weight, so they're likely to recall themselves being lighter than they actually are. That may account for an over representation of people who are actually in the obese categories that in this article would appear to be in the overweight category.
AUBREY: So it's possible that the increased risk of mortality sets in at a slightly higher BMI. Academics will likely continue to debate and study this point, but Tim Byers says the important message is that there is a growing body of evidence to suggest that weight can impact mortality as well as the onset of many diseases.
Dr. BYERS: I think this study should be a reminder to us that we need to stabilize our weight through taking small steps.
AUBREY: Even if it is just choosing, as Byers is now, to climb the four flights of stairs to his office each day instead of taking the elevator.
Allison Aubrey, NPR News, Washington.