The findings led some health care experts to dispute the notion Tuesday that obesity is simply a personal choice. They say that finding ways to improve fitness needs more attention from the government, employers as well as the food and beverage industry.
The organization that tracked obesity on a state-by-state basis, Trust for America's Health, said better information and access are the keys to improving health.
"If we're urging people to walk more, and their streets are not safe, that's an unrealistic expectation," said Jeff Levi, the group's executive director. "If we're urging people to eat more fresh fruits and vegetables, and they don't have access to a supermarket or the cost is beyond their capacity, then we're not asking them to take responsibility for something they have control over."
Levi's organization found that nine of the 10 states with the highest obesity rates are in the South: Mississippi continued to lead the way. An estimated 29.5 percent of adults there are considered obese. It's followed by Alabama and West Virginia.
Meanwhile, Colorado remains the leanest state. About 16.9 percent of its adults are considered obese. That mark was also up slightly from last year's report, but not enough to be considered statistically significant.
The only state that experienced a decrease in the percentage of obese adults last year was Nevada.
"Obesity now exceeds 25 percent in 13 states, which should sound some serious alarm bells," Levi said.
Health officials warn that a high incidence of obesity in a particular state doesn't mean it treats the issue less seriously than others. States have different challenges to contend with, said Dr. Janet Collins of the Centers for Disease Control and Prevention.
"Populations are not equal in terms of experiencing these health problems," Collins said. "Low-income populations tend to experience all the health problems we worry about at greater rates."
Trust for America's Health made scores of recommendations for reducing obesity. For example:
The group also makes recommendations for individuals. But the recommendations that people eat well and exercise are known to Americans. And clearly, many just don't care to follow.
Collins said tobacco use is another area that could be labeled a personal choice, but government agencies have taken many steps to provide people with the environment and information they need to help them make their choices. The same should be done with obesity.
The report says the health costs associated with obesity are in the billions of dollars annually. Citing a 2004 report, the advocacy group said $5.6 billion could be saved when it comes to treating heart disease if just one-tenth of Americans began a regular walking program.
The group's estimate of obesity rates is based on a three-year average, 2003-2005. The data comes from an annual random sampling of adults via the telephone. The information is designed to help the government measure behavioral risks among adults.
The government equates obesity with a body mass index, or BMI, of at least 30. Someone who is 5-feet-4 would have to weigh 175 pounds to reach that threshold.
The index is calculated by dividing a person's weight in pounds by his height in inches, squared, and multiplying that total by 703. For some people, particularly athletes who exercise a great deal, the BMI index could show them as being obese when in fact they are in excellent physical condition.