In three states--Alabama, Mississippi, and Tennessee--the prevalence of self-reported obesity among adults age 18 or older was above 30 percent in 2007, according to a report by the Centers for Disease Control and Prevention.

Overall, the proportion of U.S. adults who self report they are obese increased nearly 2 percent between 2005 and 2007, according to the report

An estimated 25.6 percent of U.S. adults reported being obese in 2007 compared to 23.9 percent in 2005, an increase of 1.7 percent. The report also finds that none of the 50 states or the District of Columbia has achieved the Healthy People 2010 goal to reduce obesity prevalence to 15 percent or less.

Colorado had the lowest obesity prevalence at 18.7 percent. Obesity is defined as a body mass index (BMI) of 30 or above. BMI is calculated using height and weight. For example, a 5-foot, 9-inch adult who weighs 203 pounds would have a BMI of 30, thus putting this person into the obese category.

"The epidemic of adult obesity continues to rise in the United States indicating that we need to step up our efforts at the national, state, and local levels," said Dr. William Dietz, director of CDC's Division of Nutrition, Physical Activity, and Obesity. "We need to encourage people to eat more fruits and vegetables, engage in more physical activity and reduce the consumption of high calorie foods and sugar sweetened beverages in order to maintain a healthy weight."

The study found that obesity is more prominent in the South, where 27 percent of respondents were classified as obese. The percentage of obese adults was 25.3 in the Midwest , 23.3 percent in the Northeast, and 22.1 percent in the West.