ATLANTA -- Obesity rates in U.S. women seem to be staying level, and the rate in men may be hitting a plateau now, too, according to a new government report released Wednesday.
With more than 72 million Americans counted as obese, adult obesity rates for both sexes seem to be holding steady at about 34 percent, the U.S. Centers for Disease Control and Prevention reported.
The rates are still too high, said Mark Swanson, a researcher who studies childhood obesity and school nutrition at the University of Kentucky's College of Public Health.
"Until the numbers start to go the other direction, I don't think we can consider this a success at all," he said.
The adult obesity rate has generally been climbing since 1980, when it was 15 percent. The entire adult population has grown heavier, and the heaviest have become much heavier in the last 25 years. Obesity is major risk factor for heart disease, certain types of cancer and type 2 diabetes.
The CDC's new report is based on a comprehensive survey by the federal government that includes physical examinations. The results are based on what was found in about 4,400 adults ages 20 and older in 2005 and 2006.
About 33 percent of men and 35 percent of women were obese. The new rates were slightly higher than the 31 percent and 33 percent reported in 2003-2004 surveys.
However, in generalizing the results to the U.S. population, researchers calculated a margin of error that swallows up the differences between years. In other words, the increases were not considered statistically significant.
The obesity rate for women has been about steady since 1999-2000, at around 33 percent. But the male rate trended up, from 27.5 percent in 1999-2000. People with a body-mass index — a standard measure of height and weight — of 30 or greater are defined by the CDC as obese.
The new CDC report compared data over four years. While it looks like the male rate is leveling off, more years will be needed to confirm a trend, said Dr. William Dietz, a CDC expert.
If there is a trend, perhaps women are having an influence on the eating and exercise habits of men, Dietz added.
Childhood obesity rates for 2005-2006 have not been released yet. Through 2003-2004, they were rising.
So what might be behind leveling adult rates?
Increased exercise is one possibility. Last week, the CDC released results of a national telephone survey that found that about half of men and women reported getting regular physical activity in 2005, an increase from the rates reported in 2001.
Physical activity prevents new cases of obesity, but it's not clear that explains the new findings, CDC officials said.
Experts believe reducing consumption of high-calorie and fatty foods have an impact.
Some restaurants cut back their super-size servings in recent years and that may be helping, said J. Justin Wilson. He's a senior research analyst for the Center for Consumer Freedom, a nonprofit coalition of restaurants and food companies.
In the new report, obesity was most common in adults aged 40 to 59.
There were large differences by race for women — the female obesity rates in the 40 to 59 age group were 39 percent in white women, 51 percent in Mexican-American women and 51 percent in black women.
However, there were no racial or ethnic disparities in the male obesity rates, the CDC said.
The report also found that about a third of obese adults had not been told by a doctor or health care provider that they were overweight. That statistic has held about steady from earlier years, said Cynthia Ogden, a co-author of the report.