Heavy teens are often destined for skyrocketing weight gain in their 20s, a new study shows.
About half of obese teen girls and a third of boys become severely obese by the time they are 30 -- meaning they are 80 to 100 pounds over a healthy weight, the research says.
"We see a tremendous amount of weight gain during those years," says researcher Penny Gordon-Larsen, associate professor of nutrition at the University of North Carolina-Chapel Hill.
Other studies have found that heavy children are more likely to be heavy adults. But this is one of the first to show what happens to teens who are obese -- 30 or more pounds overweight -- as they reach adulthood.
A third of U.S. kids and teens are overweight; two-thirds of adults are overweight or obese. Extra pounds put people at increased risk of type 2 diabetes, heart disease and many cancers.
Researchers reviewed national height and weight records of almost 9,000 people ages 12 to 21 who were followed for 13 years. Among the findings in today's Journal of the American Medical Association:
*51% of obese teen girls and 37% of obese teen boys became severely obese by age 30.
*Three-quarters of severely obese teens remained so at 30.
*1%-2% of normal-weight teens were severely obese by 30.
*Normal-weight teens gained an average of 37 pounds from their teens to age 30.
Some weight gain is normal as teens move into adulthood, Gordon-Larsen says. But they often exercise less than they did in high school or college, and they may eat in restaurants more and fall victim to large portion sizes.
"They are not building exercise into their daily routine," Gordon-Larsen says. "You need a high level of physical activity -- an hour to an hour and a half a day -- to lose or maintain your weight."
To see more of USAToday.com, or to subscribe, go to http://www.usatoday.com
Copyright 2009 USA TODAY, a division of Gannett Co. Inc.