WASHINGTON, July 9 (RIA Novosti) - Americans are continuing to get fat with around 80 million people out of a population of 306 million now classed as obese, a new study by the Center for Disease Control and Prevention said.

Despite public health warnings and campaigns promoting a healthy lifestyle, 26.1% of people in the United States are clinically obese, with six states - Alabama, Mississippi, Oklahoma, South Carolina, Tennessee and West Virginia - registering obesity rates of over 30%.

"The proportion of U.S. adults who are obese increased to 26.1% in 2008 compared to 25.6% in 2007," a statement on the CDC website said.

Respondents were asked to provide their height and weight in a telephone survey that involved 400,000 Americans aged 18 and over, the world's largest such poll. The data was used to calculate each person's body mass index. People with a BMI of 30 or over are considered obese.

Dr. William Dietz, the head of CDC's Division of Nutrition, Physical Activity and Obesity, said obesity was a leading factor in a number of diseases, including heart disease and diabetes.

"As obesity increases among all age groups, we are seeing chronic diseases in much younger adults compared to a few decades ago," Dietz said, "For example...conditions such as type 2 diabetes that were unheard of in the past."

Colorado was the only state where less than 20% of the population were considered obese.

The CDC warned that the problem is getting worse and could lead to increased prevalence of obesity-related diseases and higher health care costs.