After three decades of increases, adult obesity rates for Americans in 2012 held steady in virtually all 50 states, although rates remain high in 13 of those states, according to a report from the Centers for Disease Control and Prevention released Friday.
A national telephone survey conducted annually by the CDC found that at least 30 percent of adults were obese in several states, most of them in the South and the Midwest.
The survey asks adults their height and weight. Overall, nearly 28 percent of Americans were obese in 2012, which is roughly the same level since 2008.
Louisiana and Mississippi led the list, with nearly 35 percent of adults in both states qualifying as obese. And at least 30 percent of adults counted as obese in Alabama, Arkansas, Indiana, Iowa, Kentucky, Michigan, Ohio, Oklahoma, South Carolina, Tennessee and West Virginia.
Arkansas was the lone exception to the stability; its obesity rate increased to 34.5 percent in 2012, up from 30.5 percent in 2011.
Colorado was the thinnest state, with 20.5 percent of adults qualifying as obese in 2012. However, back in 1980 that number was only 15 percent.
"A plateau is better than rising numbers. But it’s discouraging because we're plateauing at a very high number," said Kelly Brownell, a Duke University obesity expert.
Other categories showing higher rates included people who did not complete high school and those earning less than $25,000 a year, according to the report.
It's not surprising that the South and Midwest top the charts year after year, experts say, because many states in those regions have higher poverty rates.
"When you have a limited income, you have to buy foods that are cheap. And foods that are cheap tend to have a lot of sugar and salt and fat,” said Dr. George Bray, an obesity expert at Louisiana State University.
The data appears in "F as in Fat: How Obesity Threatens America's Future," produced by the nonprofit Trust for America's Health and the Robert Wood Johnson Foundation.
"After decades of bad news, we’re finally seeing signs of progress," researchers for the two groups wrote in the report, which said that government efforts to encourage healthier diets and more exercise were paying off.
But even if current rates hold steady, aging baby boomers with obesity-related illnesses, along with a fast-rising number of Americans classed as extremely obese, will both be a burden on the nation's health care system. In 2008 the CDC estimated total obesity-related costs at $147 billion.
Rates for those ages 45 to 65, the bulk of the baby boomer generation, were 30 percent or higher in 41 states. In Alabama and Louisiana, their rate reached 40 percent.
The CDC defines as obese someone whose body-mass index (a ratio of weight to height) hits 30 or higher. A 5-foot-9 person would be considered obese at 203 pounds or more.
Friday's study, with its self-reported data, is not considered as accurate as another CDC survey, which weighs and measures participants. Since the middle of the last decade, that survey has found that around 35 percent of U.S. adults are obese.
The story may be different with children. A CDC study released last week showed, for the first time, slight drops in obesity for low-income preschoolers in 18 states.
Experts called that report encouraging, but noted that it studied children fed through a federal program providing food vouchers and other services. The decline in obesity was largely attributed to program changes instituted in 2009 that eliminated juice from infant food packages, provided less saturated fat and made it easier to buy fruits and vegetables.
In June, the American Medical Association voted to officially recognize obesity as a disease that requires a number of medical interventions.
The decision was announced at the AMA's annual meeting in Chicago. Board member Dr. Patrice Harris said that "recognizing obesity as a disease will help change the way the medical community tackles this complex issue that affects approximately one in three Americans."