The number of states with an obesity prevalence of 30 percent or more has tripled in two years to nine states in 2009, according to the August Vital Signs report from the Centers for Disease Control. In 2000, no state had an obesity prevalence of 30 percent or more.

“The big picture is that over the past several decades, obesity has increased faster than anyone could have imagined it would,” CDC director Thomas Frieden said in a press briefing accompanying the report. “Obesity has doubled in adults and tripled in children.”

Obesity is a major public health issue, with 26.7 percent of American adults – 72 million - considered obese, a 1 percent increase—an additional 2.4 million people—in the self-reported prevalence of obesity between 2007 and 2009 among adults aged 18 and over. The report also finds no state met the nation's Healthy People 2010 goal to lower obesity prevalence to 15 percent.

“We need intensive, comprehensive and ongoing efforts to address obesity,” says Frieden. “If we don't more people will get sick and die from obesity-related conditions such as heart disease, stroke, type 2 diabetes and certain types of cancer, some of the leading causes of death.”

The report also notes the medical costs associated with obesity are high. In 2008 dollars, medical costs associated with obesity were estimated at $147 billion. People who are obese had medical costs that were $1,429 higher than those of normal weight, the report said.

The new data comes from the Behavioral Risk Factor Surveillance System, which contains state-level public health data and provides a way for states to monitor progress toward Healthy People goals. To assess obesity prevalence, approximately 400,000 phone survey respondents were asked to provide their height and weight, which was used to calculate their body mass index. An adult is considered obese if he or she has a body mass index of 30 or above.

If anything, Behavioral Risk Factor Surveillance System obesity data tends to underestimate obesity prevalence because people often say they are taller than they actually are and women often say they weigh less than they do in telephone surveys. As a result, according to William Dietz, director of CDC's Division of Nutrition, Physical Activity and Obesity, the overall obesity prevalence estimate of 26.7 percent is 7.2 percentage points lower than the national 2007-2008 estimate of 33.9 percent (nearly 73 million people) from the National Health and Nutrition Examination Survey, for which individuals' height and weight were measured rather than self-reported.

The data shows how obesity affects some populations more than others. The highest prevalence was found among non-Hispanic blacks overall, whose rate was 36.8 percent, and non-Hispanic black women, whose rate was 41.9 percent. The rate for Hispanics was 30.7 percent. The rate among all non-high school graduates was 32.9 percent. Obesity prevalence was also higher in some regions than others. The South had an obesity prevalence of 28.4 percent while the Midwest had a prevalence of 28.2 percent.

“Obesity is a complex problem that requires both personal and community action,” says Dietz. “People in all communities should be able to make healthy choices, but in order to make those choices there must be healthy choices to make. We need to change our communities into places where healthy eating and active living are the easiest path.”

Colorado was the only state with a prevalence of obesity below 20 percent. Although Dietz doesn’t know why Colorado differs from other states, he suspects that it may have something to do with the fact that the state encourages physical activity, investing some of its state lottery funds in infrastructure to support it.

“There has not yet been an example of widespread, statewide change to reduce the prevalence of overweight or obesity,” says CDC’s Frieden. His recommendations for reducing or preventing obesity include increasing physical activity, breastfeeding infants, increasing fruits and vegetable in the diet, and reducing the intake of high-calorie foods and in particular, sugary drinks.