July 18 (Bloomberg) -- The populations of 45 U.S. states grew fatter, making it harder for the country to meet a 2010 target of reducing obesity to 15 percent, the Centers for Disease Control and Prevention said.

Kentucky, Louisiana, South Carolina, Virginia and West Virginia were the only states where obesity was less prevalent last year than in 2005, the Atlanta-based CDC said in a report today. The agency cited estimates derived from individuals' self- reported data. While Colorado had the lowest prevalence of obesity, at 18.7 percent, its rate climbed from 17.4 percent two years earlier, researchers said.

The proportion of U.S. adults who reported being obese in 2007 rose to a record 25.6 percent, which would include about 54 million people. That's 1.7 percent higher than two years earlier, the researchers said. CDC officials said the survey shows the 2010 target, set in 2000 by public and private health groups, may be elusive, leaving millions at risk for heart disease and diabetes.

``It's going to certainly be a struggle to get down to 15 percent, particularly for the country as a whole,'' said Deborah Galuska, associate director for science at the CDC's Division of Nutrition, Physical Activity and Obesity, in a telephone interview today.

The agency estimates actual obesity at 34 percent of the population, rather than the lower figure based on the survey, Galuska said. The CDC figure takes into account that people can sometimes be less than truthful about their height and weight, she said.

Healthy People 2010

Healthy People 2010, a set of health goals established by federal scientists in January 2000, calls for obesity to be reduced to 15 percent of U.S. adults by 2010, according to program's Web site.

The prevalence of obesity among adults age 18 years or older was 25 percent to 29 percent in 28 states, including New York, Texas, and Illinois, according the 2007 telephone survey of 350,000 people conducted by Atlanta-based CDC.

In three states, Alabama, Mississippi and Tennessee, more than 30 percent of people were obese. The South was the U.S.'s heaviest region at 27.3 percent, the report said.

About 72 million Americans age 20 and older are considered obese under current U.S. guidelines, the CDC said in a December report based on interviews, physical examinations and laboratory tests. That report put the obesity rate at 34 percent.

To contact the reporter on this story: John Taddei in New York at jtaddei3@bloomberg.net

Last Updated: July 18, 2008 06:51 EDT