As US obesity epidemic grows, new study shows who is gaining weight over the last decade

Research looked at the long-term weight gain of more than 13,800 U.S. adults -- a rare data point unearthed in obesity research. The study shows more than half of American adults gained 5% or more body weight over a 10-year period and more than a third of American adults gained 10% or more body weight. Just under a fifth gained 20% or more body weight.