More people are putting on weight than ever. It now appears that much of this extra weight comes early in adulthood. In a new study published in the Journal of Obesity, researchers at Brigham Young University collected data on 10-year weight change patterns from almost 14,000 American adults from the National Health and Nutrition Examination Survey. More than half of Americans gained 5 percent or more body weight during a 10-year period. More than one-third of Americans gained 10 percent or more body weight. And nearly one-fifth gained 20 percent or more body weight. Surprisingly, a large percentage of those extra pounds were added in early adulthood. The average American gained about 17.6 pounds from their mid-20s to mid-30s. By their fifties and sixties, though, the average weight gain was less than five pounds.