adn't been severely obese as teens were now classified as severely obese adults. Black women were the most likely to become severely obese as adults, reported the study.
Teens who were obese at the beginning of the study were 16 times more likely to become severely obese adults compared to normal-weight or overweight teens.
"This is really setting these kids up to have significant health challenges later in life," said Gordon-Larsen.
"We need to try to intervene and prevent obesity early in life, and if we have an obese adolescent, we really need to work to prevent severe obesity," she said.
"I wasn't especially surprised by the study's findings. Other research has also shown that weight during adolescence is very predictive of weight in adulthood," said Dr. Goutham Rao, clinical director of the Weight Management and Wellness Center at Children's Hospital of Pittsburgh.
And getting teenagers to change their habits may be difficult, he noted. "If you have a 3-year-old, it's relatively easy to influence that child's eating habits because you provide all the food. With adolescents, it's much more complicated because they're often making their own food and drink choices and their habits are more entrenched," he said.
But parents still provide the bulk of food in a teen's diet and can set up a healthy food environment at home by not providing sweetened beverages and making healthy snacks, like fruits and vegetables, available, he added.
Other important tips, he said, are to limit fast-food consumption to no more than once a week, limit screen time to two hours a day, and to encourage some exercise every day. It's also important to try to have at least one parent eat dinner with your teenager most days of the week.
One bright note in this study was that about 30 percent of severely obese teens didn't go on to become severely obese adults, suggesting that it is possible to change even entrenched lifestyle habits.
And "the younger they are, the more chances you have to make changes," added Rao.
The Weight-control Information Network has information for teens on healthy lifestyle habits.