Obesity rates among U.S. adults have more than doubled from the 15 per cent of 1980. In that same time, they have more than tripled among children.

Since the CDC found that the percentage of obese children and adults was essentially unchanged between 2008 and 2010, some experts question whether the “F as in Fat” model overstates future obesity by assuming past trends continue in a straight line.

“This is a strong assumption,” said economist Justin Trogdon of RTI International in North Carolina. “Recent evidence from other surveys suggest obesity rates may be leveling off.”

Mathematician Martin Brown of Britain’s National Heart Forum, a nonprofit group, who led development of the model, said it takes a longer view by design.

“You have to take trends over a number of years,” he said. “In the age groups that matter, there just isn’t much evidence of a leveling off in obesity rates.”

EDUCATION AND INCOME

Obesity has long been associated with education and income. The report found that about one-third of adults without a high school diploma were obese, compared with about one-fifth of those who graduated from college or technical college.

And one-third of adults who earn less than $15,000 per year are obese, compared to one-quarter of those who earned $50,000 or more per year. The obesity-poverty connection reflects such facts that calorie-dense foods are cheap and that poor neighbourhoods have fewer playgrounds, sidewalks and other amenities that encourage exercise.

As a result, many states projected to have the most obesity in 2030 do now, too. In 2011, 12 states had an adult-obesity rate above 30 per cent, with Mississippi the highest at 34.9 per cent. Colorado was the lowest at 20.7 per cent.

The report projects that in 2030 in Mississippi, 66.7 per cent of adults will be obese, as will 44.8 per cent in Colorado, which will still be the thinnest state.

More surprising are projections for states such as Delaware, now ranked 19 for obesity with a rate of 28.8 per cent. The model uses 1999 as a baseline, explained Brown. “So if a state had a low rate of obesity in 1999 and is fairly high now, that indicates a steep rate of increase, which we believe will not go away.” Result: an obesity rate of 64.7 per cent in Delaware in 2030, making it the third-most obese state.

States facing the greatest percentage increase in obesity-related medical costs are now in the middle of the pack.

New Jersey faces the largest increase in costs, 34.5 per cent, as its obesity rate is projected to climb from 23.7 per cent today to 48.6 per cent in 2030. Eight other states could see increases of 20 per cent and 30 per cent, including New Hampshire, Colorado and Alaska.

Trust for America’s Health sees room to change that trajectory with the right interventions.

“We have learned that with a concerted effort you can change the culture of a community, including its level of physical activity, eating habits, what foods are offered in schools, and whether families eat together,” said Levi.

In New York City, for instance, obesity for elementary and middle-school students dropped 5.5 per cent from the 2006-07 school year to 2010-11, thanks mostly to healthier school lunches, public health experts said.

“A lot of this is about making healthy choices easier and not mandating healthier lifestyles,” Levi said