Being overweight is nowhere near the killer that the government believed, ranking No. 7 instead of No. 2 among the nation's preventable causes of death, according to a startling new calculation from the Centers for Disease Control and Prevention.

CDC researchers reported that packing on too many pounds accounts for 25,814 deaths a year in the United States. As recently as January, the agency came up with an estimate 14 times higher: 365,000 deaths.

The latest calculation immediately was seized upon by skeptics who argue that public-health authorities have created undue alarm about obesity. Other experts and the researchers who conducted the new study, however, said obesity still clearly represents a major public-health threat.

"This certainly shouldn't be interpreted to mean obesity isn't a problem anymore," said Katherine Flegal of the National Center for Health Statistics, who led the study in today's issue of the Journal of the American Medical Association. "Obesity certainly is still a problem."

Flegal attributed the difference in estimates to the fact that her group used more-recent and more-complete data and was able to account better for more variables, such as smoking, age and alcohol consumption. Flegal and her colleagues also speculated that improvements in medical care and lifestyles may have begun to reduce obesity's toll.

"People have been changing their diets in response to some of the public-health activities around obesity, which has been having a positive effects on such factors as cholesterol levels," she said.

The number of Americans who are overweight has been increasing steadily in recent years. About two-thirds of Americans are overweight, including about one-third who are obese. Being overweight is believed to increase the risk for a host of health problems, including heart disease, cancer and diabetes.

The CDC last year estimated that being overweight was causing nearly 400,000 deaths each year, making it the No. 2 cause of preventable death. The agency predicted that obesity soon would overtake tobacco as the leading cause of preventable death, but it subsequently acknowledged that its estimate involved a statistical error and lowered it.

In the new study, Flegal and her colleagues used data collected in three periods between 1971 and 2000 by large federal surveys called the National Health and Nutrition Examination Surveys.

Based on measurements of height and weight and other information about health, lifestyle and mortality, the new study attributes 111,909 deaths to obesity. Surprisingly, the scientists reported that people who were merely overweight — as opposed to obese — suffered more than 86,000 fewer deaths than those whose weight was in the so-called healthy range.

Using the new estimate, excess weight would drop to the No. 7 preventable cause of death, behind tobacco, alcohol, germs, toxins/pollutants, car crashes and guns.

Because of the uncertainty in calculating health effects of being overweight, CDC Director Dr. Julie Gerberding said, the agency will not use the new figure 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," said Gerberding, adding that the CDC will work to improve methods for calculating the consequences of obesity.

Nevertheless, critics seized on the new findings as evidence of "scare-mongering" by the CDC and other public-health authorities.

"It's a scandal that the CDC's 400,000-deaths estimate didn't use this information, which was readily available on the agency's computers," wrote Rick Berman of the Center for Consumer Freedom, an advocacy group funded by the restaurant and food industries, in a letter to Gerberding. "The American public deserves to know where the CDC stands on this greatly reduced number and whether obesity is truly worse than the Black Death, as you have stated."

Flegal and her colleagues speculated that some of the difference in the two estimates may be due to recent improvements in treating heart disease, a major cause of death among the obese.

In addition, Flegal noted that the latest study looked only at mortality and not at other negative effects that obesity has on quality of life.

Other health authorities agreed, and said the findings should not undermine efforts to fight obesity.

"Obesity prevalence is increasing in adults and in the young, and we may not see that impact on cardiovascular disease and death until the next three to four decades," said Robert Eckel of the American Health Association.

Material from the Los Angeles Times is included in this report.