(Corrects metric conversion, paragraph 11)
* In 13 states, more than 60 percent of adults are projected to be obese
* Additional medical costs could reach $66 billion per year
By Sharon Begley
NEW YORK, Sept 18 (Reuters) - If Americans stick to their eating and exercise habits, future historians will look back on the early 21st century as a golden age of svelte.
The latest in a long string of reports on the obesity epidemic in the United States presents the usual glum picture of the present, when 35.7 percent of adults and 16.9 percent of children age 2 to 19 are obese, as the Centers for Disease Control and Prevention (CDC) reported earlier this year.
But for the first time, the report from the Trust for America's Health and the Robert Wood Johnson Foundation - the ninth that the groups have issued - also applies a time machine to those data. Using a model of population and other trends, the report "F as in Fat" projects that, by 2030, unless Americans change their ways, half of U.S. adults will be obese.
Building on the state-by-state obesity data CDC released in August, "F as in Fat" projects obesity rates of at least 44 percent in every state and over 60 percent in 13.
Since obesity raises the risk of numerous diseases, from type 2 diabetes to endometrial cancer, that will mean more sick people and higher medical costs, notes the report, released Tuesday.
In particular, it projects as many as 7.9 million new cases of diabetes per year, compared to 1.9 million new cases in recent years. There could also be 6.8 million new cases of chronic heart disease and stroke every year, compared with 1.3 million new cases per year now.
The increasing burden of illness will go right to the bottom line, it says: $66 billion more in annual obesity-related medical costs over and above today's $147 billion to $210 billion (out of total healthcare spending of $2.7 trillion).
That projection supports a study published earlier this year in the American Journal of Preventive Medicine that found that by 2030, 42 percent of U.S. adults could be obese, adding $550 billion to healthcare costs over that period.
As with all projections, from climate models to Dickens' "A Christmas Carol," human actions can prevent the worst of the scenarios.
"This is a tale of two futures," said Jeffrey Levi of George Washington University and the executive director of Trust for America's Health. "We're at a turning point where if we don't do something now to mitigate these trends, the cost in human health and healthcare spending will be enormous."
Obesity is defined as having a body mass index (BMI) above 30. Overweight means a BMI of 25 to 29.9. BMI is calculated by taking weight in pounds and dividing it by the square of height in inches, and multiplying the result by 703. For instance, someone who is 5 feet, 5 inches (1.6 meters) tall and weighs 185 p ound s (84 k g ) has a BMI of 30.8.
The projections emerge from the increase in obesity rates among U.S. adults, which have more than doubled from the 15 percent of 1980, and children, which have more than tripled since 1980.
Although the percentage of obese children and adults was essentially unchanged between 2008 and 2010, CDC found, the "F as in Fat" model takes a longer view, explained mathematician Martin Brown of Britain's National Heart Forum, a nonprofit group, who led development of the model.
"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."
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 percent, with Mississippi the highest at 34.9 percent. Colorado was the lowest at 20.7 percent.
The report projects that in 2030 in Mississippi, 66.7 percent of adults will be obese, as will 44.8 percent in Colorado, which will still be the thinnest state.
More surprising are projections for states such as Delaware, now the 19th-most obese state with a rate of 28.8 percent. 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 percent 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 percent, as its obesity rate is projected to climb from 23.7 percent today to 48.6 percent in 2030. Eight other states could see increases of 20 percent and 30 percent, including New Hampshire, Colorado and Alaska.
All is not lost, said Levi. "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," he said.
In New York City, for instance, obesity in grades K-8 dropped 5.5 percent from the 2006-07 school year to 2010-11, thanks mostly to healthier school lunches, public health experts said.
If BMI were reduced by 5 percent - for an adult of average weight, that means losing 11 pounds (5 kg) - in 2030 the obesity rate would not exceed 60 percent in any state, in contrast to the 13 in the business-as-usual projection. (Editing by Philip Barbara)