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.

Adult obesity 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 a major risk factor for heart disease, certain types of cancer and type 2 diabetes.

The 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 2003-04 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, about 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 2005-06 have not been released yet. Through 2003-04, they were rising.

Increased exercise is one possibility that might be behind leveling adult rates. 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.