CHICAGO -- Being overweight is nowhere near as big a killer as the government thought, ranking No. 7 instead of No. 2 among the nation's leading preventable causes of death, according to a startling new calculation from the CDC.

	Online Graphic See a graphic that shows the number of deaths linked to weight issues going back to 1971.

The Centers for Disease Control and Prevention estimated yesterday that packing on too many pounds accounts for 25,814 deaths a year in the United States. As recently as January, the CDC came up with an estimate 14 times higher: 365,000 deaths.

The new analysis found that obesity -- being extremely overweight -- is indisputably lethal. But like several recent smaller studies, it found that people who are modestly overweight actually have a lower risk of death than those of normal weight.

Biostatistician Mary Grace Kovar, a consultant for the University of Chicago's National Opinion Research Center in Washington, said "normal" may be set too low for today's population. Also, Americans classified as overweight are eating better, exercising more and managing their blood pressure better than they once did, she said.

The study -- an analysis of mortality rates and body-mass index, or BMI -- was published in today's Journal of the American Medical Association.

Last year, a CDC study listed the leading causes of preventable death in order as tobacco; poor diet and inactivity, leading to excess weight; alcohol; germs; toxins and pollutants; car crashes; guns; risky sexual behavior; and illicit drugs.

Using the new estimate, excess weight would drop behind car crashes and guns to seventh place -- a ranking that the CDC is unwilling to make official, underscoring the controversy inside the agency over how to calculate the health effects of obesity.

Last year, the CDC issued a study that attributed 400,000 deaths a year to mostly weight-related causes and said excess weight would soon overtake tobacco as the top U.S. killer. After scientists inside and outside the agency questioned the figure, the CDC admitted making a calculation error and lowered its estimate three months ago to 365,000.

The new study attributes 111,909 deaths to obesity, but then subtracts the benefits of being modestly overweight, and arrives at the 25,814 figure.

CDC Director Dr. Julie Gerberding said that because of the uncertainty in calculating the health effects of being overweight, the CDC is not going to use the new figure of 25,814 in its public awareness campaigns. And it is not going to scale back its fight against obesity.

"There's absolutely no question that obesity is a major public health concern of this country," she said. Gerberding said the CDC will work to improve methods for calculating the consequences of obesity.

CDC spokesman Tom Skinner said the agency will probably start using a range of estimates for obesity-linked deaths.

Dr. JoAnn Manson, chief of preventive medicine at Brigham and Women's Hospital in Boston, said she is not convinced that the new estimate is right.

"I think it's likely there has been a weakening of the mortality effect due to improved treatments for obesity," she said. "But I think this magnitude is surprising and requires corroboration."

The analysis was led by Katherine Flegal, a senior research scientist with the CDC's National Center for Health Statistics. The study that had to be corrected was conducted by a different arm of the CDC, the Division of Adult and Community Health, and its authors included Gerberding.

One major reason for the far lower number in this latest study is that it used more recent data, researchers said.

A related study, also in today's JAMA, found that overweight Americans are healthier than ever, thanks to better maintenance of blood pressure and cholesterol levels. Diabetes is on the rise among people in all weight categories, however.