In a recent study of high school students in Philadelphia, researchers found that 14% were obese. The good news is that three-quarters of these obese teens said they were trying to lose weight. The bad news is they appeared to be going about it all wrong.
Led by Clare Lenhart, a doctoral candidate in public health at Temple University, researchers looked at data from the 2010 Philadelphia Youth Risk Behavior Survey, which included 43,753 students from the city’s public high schools. Data collected in the survey covered a wide range of lifestyle behaviors and health measures like obesity, recent smoking, daily soda consumption, exercise and hours per day playing video games.
Of the 5,994 respondents who were considered obese, 76% said they were actively trying to lose weight. But their other behaviors suggested that they were confused about healthy weight loss. Obese students who were trying to slim down were nearly twice as likely to smoke as obese kids who weren’t trying to lose weight, for instance. Obese girls were 40% more likely to exercise for at least 60 minutes a day, compared with their non-dieting counterparts — a heartening finding — but they were also nearly three times as likely to drink sugary soda every day. Further, obese boys who said they wanted to lose weight were more than three times as likely to be sedentary and 47% more likely to play video games for three hours every day, compared with other obese boys.
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“From a health education standpoint, finding out that three-quarters of students who are obese want to lose weight is exactly what we want,” said Lenhart in a statement. “But the behavior they’re engaging in is puzzling; it’s counterproductive to what they’re trying to do.”
“For example, among the girls who are exercising, they may not realize that one soda could undo that 30-minute walk they just took,” Lenhart said.
The findings suggest that obesity experts may need to drill down from the community and school levels to find out what individual teens are doing to try to lose weight. Most anti-obesity efforts focus on public-health measures like banning sodas from schools, but there isn’t much data on whether teens really understand the nutrition and exercise messages that are key for healthy weight.
One way to find out, Lenhart says, is to get family doctors to ask. “If a child is going to their pediatrician, and the doctor asks if they’re losing weight, an appropriate follow up question might be, ‘How are you doing that?'” she said. “It could help guide those teens to more productive weight loss activities.”
The current study, which was presented on Tuesday at the annual meeting of the American Public Health Association, is not peer-reviewed for publication and must be considered preliminary.
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Meredith Melnick is a reporter at TIME. Find her on Twitter at @MeredithCM. You can also continue the discussion on TIME’s Facebook page and on Twitter at @TIME.