Nov. 9, 2010 -- Obese teens are at risk of becoming severely obese as adults, according to a new study.
"What's unique about this study is, we are following them over 13 years," says researcher Penny Gordon-Larsen, PhD, associate professor of nutrition at the University of North Carolina, Chapel Hill.
She expected to see an increased risk of severe obesity during young adulthood in those teens who were obese, but the percentages were higher than she anticipated, she tells WebMD.
"Half of the obese female teens developed severe obesity by their 30s, and 37% of the obese male teens developed severe obesity," she says.
Severe obesity is defined as having a body mass index (BMI) of 40 or greater. "When we are talking about severe obesity, we are talking about 80 to 100 pounds over normal body weight," Gordon-Larsen says.
The excess weight carries with it an increased risk of health complications, such as high blood pressure, diabetes, asthma, and arthritis.
The study is published in TheJournal of the American Medical Association.
Tracking Obese Teens
While much research has shown that obesity and severe obesity have risen in recent years, there has been less research that looks at those who are obese early in life to see what happens as they enter young adulthood, Gordon-Larsen says.
She tracked 8,834 participants in the U.S. National Longitudinal Study of Adolescent Health, ages 12 to 21 when they entered the study in 1996. She followed them into adulthood, when they were ages 24 to 33 in 2007-2009.
Weight and height were measured during in-home surveys and body mass index was calculated. Participants came from 80 high schools and 52 middle schools and are representative of the U.S. population.
At the study's start in 1996, just 1% of the teens, or 79, were severely obese. Sixty of those, or 70.5%, remained severely obese in adulthood.
By 2009, 703 new cases of severe obesity -- or 7.9% of all the participants -- were found in those young adults who weren't severely obese as teens. Those 703 were more likely to have a higher BMI as a teen than those who didn't become severely obese as young adults.
Gordon-Larsen found gender and racial differences, with severe obesity rates highest among black women, with 52.4% of those who were obese as teens becoming severely obese at the study end.
Put in other terms, overall, the obese teens were 16 times more likely to develop severe obesity as young adults compared to normal-weight or overweight (but not yet obese) teens, she found.
Less than 5% of those who were at a normal weight as teens became severely obese as young adults, she found.
Those who developed severe obesity gained about 80 pounds over the 13-year follow-up, Gordon-Larsen says. "I think these numbers are pretty staggering, in terms of the amount of weight gained and the risk," she says.
The study findings are no surprise to Jessica Rieder, MD, founder and director of the Bronx Nutrition and Fitness Initiative for Teens program, or B'N'Fit, for overweight and obese teens at Montefiore Medical Center in the Bronx, N.Y. She reviewed the study findings for WebMD.
While programs to prevent childhood obesity have become more common, those to help youth already obese are less common, she says.
Advice for Parents
Gordon-Larsen tells parents of all children to "keep an eye on the weight gain."
She suggests parents have a goal of ''keeping a healthy household." That means focusing on healthy food options and building physical activity into the day, encouraging kids to walk more and move more.
Rieder agrees, suggesting that healthy changes need to be adopted by all family members, not just children who are trying to maintain or lose weight. "As a family, you adopt a healthier lifestyle for everyone," she says. "The whole family does it together."
Beyond those changes, Rieder says, ''the obese child needs a lot of support." She suggests parents of obese children and obese teens talk to their child's pediatrician and ask for screenings for diabetes, high cholesterol, and other potential problems. Ask what resources are available in the community to help your child lose weight.