One in every five teens ages 14 to 17 was classified as overweight. That rate increased to one in every three by age 24, George Patton, MD, of Royal Children's Hospital in Victoria, Australia, and colleagues reported online in the Journal of Adolescent Health.
There was a similar increase in the prevalence of obesity, from 3.6% to 6.7%.
Weight status during adolescence was predictive of weight during young adulthood. Few teens who were obese or persistently overweight achieved a normal weight by age 24.
"For these groups, clinical intervention appears warranted even though there is still much to learn about the safety and longer-term efficacy of available approaches," the researchers wrote.
A normal weight once they reached young adulthood was more common among teens who were not persistently overweight, which suggests that lifestyle interventions -- increasing physical activity and reducing caloric intake -- may be acceptable for these individuals, Patton and his colleagues noted.
The researchers followed 1,943 ninth-graders in Victoria through eight waves of follow-up from 1992 (mean age 14.9) to 2003 (mean age 24.1); 1,520 participated in the final wave.
There were substantial increases in the proportion of overweight and obese individuals from the first to the last wave, and adolescent weight status helped predict -- although not in all cases -- who would be overweight or obese as a young adult, which was consistent with previous studies, according to the researchers.
Of the adolescents who were overweight at some point, more than half (59%) were overweight at 24.
Among overweight 24-year-olds, only 33% had never been overweight as a teen; 40% had had persistently normal weight as a teen, and 80% had had a normal weight at some point during the teen years.
Persistence of overweight in adolescence appeared to affect the likelihood of being overweight at 24 -- 70% of those who were overweight on at least three follow-up visits were still overweight as a young adult, compared with 45% of those who were overweight at only one or two visits as a teen.
"For those with less persistent and less severe adolescent weight problems, overweight and obesity were much less common later, particularly in females," the researchers wrote. "Over two-thirds of all girls with less persistent overweight in adolescence were at a normal weight in young adulthood. The picture was less sanguine for males, with only 40% of those with less persistent overweight achieving a normal weight at 24 years."
Among the 24-year-olds who were obese, only 12% had maintained a normal weight throughout the teen years; 49% had been obese during at least one visit as a teen, and another 39% had been overweight at least once.
Almost two-thirds of teens who were persistently obese remained obese at 24, and no teen with persistent obesity had a normal weight at 24.
The authors noted some limitations of the study, including some missing data and the use of self-reported height and weight to determine body mass index during the two young-adult waves.
The authors reported that they had no conflicts of interest.
- Reviewed by Robert Jasmer, MD Associate Clinical Professor of Medicine, University of California, San Francisco and Dorothy Caputo, MA, RN, BC-ADM, CDE, Nurse Planner