Teens carry extra pounds into adulthood, add more

In a nationally representative study of American youth, researchers found that almost one in 12 teenagers became severely obese as they entered adulthood -- landing them some 100 pounds above their ideal weight.

And of those who were obese to begin with, about half the girls and more than a third of the boys grew into the larger-size category, raising their odds of developing heart disease, diabetes and certain types of cancers.

"People with severe obesity suffer from potentially life-threatening troubles," said Penny Gordon-Larsen, a nutrition scientist at the University of North Carolina at Chapel Hill, who led the research.

"The prevention efforts that we've had in the past maybe have not been as successful as we would have liked them to be," she added. "We truly need to prevent kids from becoming obese teenagers, and then prevent those teenagers from becoming severely obese adults."

According to the Centers for Disease Control and Prevention, medical expenses related to overweight and obesity eat up about nine percent of total U.S. medical expenditures, amounting to $147 billion in 2008.

In the meantime, the national waistline is only getting bigger. Several states now have obesity rates of more than 30 percent, with Mississippi leading the pack at 34.4 percent of residents. Colorado, with the leanest population in the nation, still has an obesity rate of 18.6 percent.

Gordon-Larsen said weight-loss drugs -- even combined with diet and lifestyle changes -- are not very effective and have side effects. Surgery, such as gastric bypass or banding, lets people shed more pounds, but comes with a big price tag and potential complications.