Maine is moving up in the national ranking for an undesirable attribute: Obesity.

The state’s adult obesity rate of 28.4 percent last year made it the 23rd most obese state, up from 25th a year earlier.

But Maine’s rate of obesity is slowing, according to a report by the Trust for America’s Health and the Robert Wood Johnson Foundation. The rise from 2011, when the rate was 27.8 percent, was not considered statistically significant, according to the report.

Maine is the most obese state in New England, the report says, followed by New Hampshire, at 28th; Rhode Island, 36th; Connecticut, 39th; Vermont, 46th; and Massachusetts, 49th.

Colorado has the lowest rate, 20.9 percent.

According to the report, called “F as in Fat: How Obesity Threatens America’s Future 2013,” obesity rates rose in 16 states in 2011, in 37 states in 2010, and in all but one state in 2005.

“While stable rates of adult obesity may signal prevention efforts are starting to yield some results, the rates remain extremely high,” said Jeffrey Levi, executive director of the Trust for America’s Health, in a prepared statement.

Obesity is determined by calculating body mass index, a ratio of weight to height.

Anyone with an index of 30 or higher is considered obese. A body mass index of 25 or higher is considered overweight. By that measure, a 5-foot, 9-inch person is considered overweight at 169 pounds and obese at 203 pounds.

Obesity rates are over 30 percent in 13 states, the report says. In 2000, no state had an obesity rate over 25 percent. And in 1980, every state’s obesity rate was below 15 percent.

“We’re pleased to see them level off,” said Bethany Sanborn, program manager for chronic disease prevention in Portland’s Public Health Division. “Now, we need to reverse that trend.”

Sanborn said the city has been working for a couple of years to help change people’s habits and “make the healthy choice the easy choice.”

Adding salad bars at all schools in the city, working with restaurants to list nutrition information on their menus and adopting a policy to make streets easier to use for pedestrians and bicyclists are among the changes that have been made, she said.

The report says Pennsylvania is the only state more obese than Maine that is not in the South or Midwest, where the highest obesity rates are concentrated.

Mississippi, which had been the most obese state since 2004, was edged out in the latest study by Louisiana, where the obesity rate is 34.7 percent.

Dr. Sheila Pinette, director of the Maine Center for Disease Control and Prevention, pointed to Maine’s poverty level and lack of access to fresh and inexpensive fruits and vegetables as reasons for the ranking.

“It’s a cultural thing,” she said.

Pinette said programs like Let’s Go!, which promotes healthy eating and regular physical activity for children, are aimed at reversing that trend.

“It’s one step at a time, one child and one person at a time,” she said.

Amy McLaughlin, who grew up in Old Town, and Andrew Bisbing, who grew up in Yarmouth, said they believe there’s a lack of education about nutrition in Maine’s schools. They believe that, along with the poverty level, could contribute to Maine’s high obesity rate.

Both are in their 20s and living in Portland. As they walked to the gym on Monday, both said they try to exercise at least five times a week.

Maine men, with a rate of 30.2 percent, are more obese than Maine women, whose rate is 26.6 percent, the report says. The most obese age group is those who are 45 to 64, with a rate of 32.5 percent. Young adults, age 18 to 25, are the least obese, with a rate of 14.9 percent.

Jackie Conn, general manager of Weight Watchers of Maine, said the aging population of Maine, which has the nation’s highest median age at 42.7 years, is the primary reason for its high ranking.

Also, she said, the amount of urban sprawl, its long winters and the condition of the roads give people reason to get in their cars to get where they’re going, rather than walk or bike.

“There is sort of a general attitude, it’s hard to do or impossible,” Conn said about exercise and weight loss.

She said she thinks the key to reversing the trend is to get the word out about easy and affordable ways to stay active, like getting up every hour and walking for five minutes, working out to a free YouTube video or cutting back on portions rather than changing what you eat.

She said people might think they have to eat expensive, organic vegetables to lose weight but canned and frozen vegetables are just as good.

The report by the Trust for America’s Health, a nonprofit organization based in Washington, D.C., and the New Jersey-based Robert Wood Johnson Foundation is based on data collected by the U.S. Centers for Disease Control and Prevention.

The CDC’s Behavioral Risk Factor Surveillance System annually surveys more than 400,000 adults about their health, including their height and weight.

The report also showed that 64.2 percent of Maine’s population is overweight, making it 26th in the nation. It also ranks 26th for its rate of diabetes, which is 9.7 percent of the population.

Leslie Bridgers can be contacted at 791-6364 or at: lbridgers@pressherald.com