WASHINGTON &#8212 Loosen the belt buckle another notch: Obesity rates continued to climb in 31 states last year, and no state showed a decline.

Mississippi became the first state to crack the 30 percent barrier for adults considered to be obese. West Virginia and Alabama were just behind, according to the Trust for America’s Health, a research group that focuses on disease prevention.

Colorado continued its reign as the leanest state in the nation with an obesity rate projected at 17.6 percent.

This year’s report, for the first time, looked at rates of overweight children ages 10 to 17. The District of Columbia had the highest percentage – 22.8 percent. Utah had the lowest – 8.5 percent.

Health officials say the latest state rankings provide evidence that the nation has a public health crisis on its hands.

Unfortunately, we’re treating it like a mere inconvenience instead of the emergency that it is,” said Dr. James Marks, senior vice president at the Robert Wood Johnson Foundation, a philanthropy devoted to improving health care.

Officials at the Trust for America’s Health want the government to play a larger role in preventing obesity. People who are overweight are at an increased risk for diabetes, heart problems and other chronic diseases that contribute to greater health care costs.

“It’s one of those issues where everyone believes this is an epidemic, but it’s not getting the level of political and policymaker attention that it ought to,” said Jeffrey Levi, the organization’s executive director. “As every candidate for president talks about health care reform and controlling health care cost costs, if we don’t home in on this issue, none of their proposals are going to be affordable.”

At the same time, many believe weight is a personal choice and responsibility. Levi doesn’t dispute that notion, but he said society can help people make good choices.

“If we want kids to eat healthier food, we have to invest the money for school nutrition programs so that school lunches are healthier,” he said. “If we want people to be more physically active, then there have to be safe places to be active. That’s not just a class issue. We’ve designed suburban communities where there are no sidewalks for anybody to go out and take a walk.”

To measure obesity rates, Trust for America’s Health compares data from 2003-2005 with 2004-2006. It combines information from three years to improve the accuracy of projections. The data come from a survey of height and weight taken over the telephone. Because the information comes from a personal estimate, some believe it is conservative.

Indeed, the Centers for Disease Control and Prevention released a study last year noting a national obesity rate of about 32 percent – a higher rate than was cited for any of the states in the Trust for America’s Health report.