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For millions of Americans, the news might seem too good to be true; according to the Centers for Disease Control and Prevention (CDC), being overweight could actually have some benefit.
"Pleasantly Plump May Be OK," reports the ABC News Web site on April 20. "CDC: Dangers of Being Overweight Overstated," the Houston Chronicle writes April 19. "Some Extra Heft May Be Helpful," says the April 20 New York Times.
Not so fast, say health experts.
BY THE NUMBERS
In an April 20 report in JAMA, CDC scientists analyze National Health and Nutrition Examination Survey (NHANES) data that show increased mortality associated with being underweight or obese compared with being normal weight and a lower risk of death among those who are overweight.1
The researchers compared data from NHANES I (1971–1975), NHANES II (1976–1980), and NHANES III (1988–1994) to estimate the number of deaths attributable to weight in 2000.
According to their analysis, there were 111,909 deaths among those with a body mass index (BMI) of >_30 compared with those within the normal BMI range of 18.5 to 25. In addition, there were 33,746 deaths linked to underweight (BMI <18.5), while a lower risk of mortality was noted among the overweight (BMI of 25–30).
But don't pass around the doughnuts to celebrate the news yet.
"We looked at death—arguably a very important health outcome, but certainly not the only one," says David F. Williamson, PhD, senior epidemiologist at CDC's diabetes division. "We have to be concerned about other health conditions obesity is related to. Right on top is diabetes."
S. Jay Olshansky, PhD, an epidemiologist at the University of Chicago School of Public Health, is concerned that media and the public may misinterpret the CDC's latest findings.
"They only looked at mortality. They didn't look at morbidity or disability associated with obesity," says Olshansky, co-author of a recent report in the New England Journal of Medicine suggesting that the burgeoning obesity epidemic may reverse a decades-long trend of growing life expectancy.2
"The risk of diabetes is still continuing to rise," Olshansky says.
Williamson agrees that the CDC report is hardly a green light for overeating and inactivity. "This is not a license to forget about one's body weight at all," he says. "This study doesn't let anybody off the hook."
An accompanying paper in JAMA indicates that obesity-related cardiovascular disease risk factors—except for the risk of diabetes—have declined in all categories of BMI.3
"We found that high blood pressure, elevated cholesterol, and smoking [rates] had improved dramatically over the last 30 to 40 years," Williamson says. "However, diabetes continued to go up, and that's largely from obesity."
REVISING STATISTICS
Nearly overlooked in the CDC's latest report is a revision of controversial statistics released in 2004. In a highly publicized news conference, the CDC unveiled a JAMA report concluding that obesity and overweight kills 400,000 Americans per year and is poised to become the nation's top preventable cause of death, a spot now held by smoking.4
Other experts questioned the statistics and the methodology behind them. After a front-page story in The Wall Street Journal did so, the CDC revisited the report and, in a nearly unprecedented move, admitted that flawed methods may have overestimated the obesity toll.5
The most recent number of almost 112,000 annual obesity-related deaths is
still lower than the revised number of 365,000 released by the CDC in January
2005. 
References
2. Olshansky SJ, Passaro DJ, Hershow RC, et al.: A potential decline
in life expectancy in the United States in the 21st century. N Engl
J Med 352:1138–1145, 2005.
3. Gregg EW, Cheng YJ, Cadwell BL, et al.: Secular trends in
cardiovascular disease risk factors according to body mass index in U.S.
adults. JAMA 293:1868–1874, 2005.
4. Mokdad AH, Marks JS, Stroup DF, et al.: Actual causes of death in
the United States, 2000. JAMA 291: 1238–1245, 2004.
5. Mokdad AH, Marks JS, Stroup DF, et al.: Correction: Actual causes
of death in the United States, 2000. JAMA 293: 293–294, 2005.
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