Findings from the school-based intervention, which involved exercise sessions and nutrition workshops for lower-income girls, are the latest disappointment in a slew of research attempting to head-off adult obesity -- and the disease risks that come with it.

Especially during the middle- and high-school years, girls' physical activity declines dramatically, according to lead researcher David Lubans, from the University of Newcastle in New South Wales, Australia.

"We were fighting against a range of psychological, sociological, environmental and biological barriers," he told Reuters Health in an email.

In the future, he added, "we need to make the programs more appealing and exciting and present information in a way that is meaningful to adolescent girls."

Lubans and his colleagues conducted their study in 12 schools in low-income areas of New South Wales. All in all, they randomly assigned 357 eighth-grade girls either to go through the intensive program at school or not to get any extra nutrition or exercise help.

At the start of the study, girls in both groups weighed an average of close to 130 pounds, with about four in ten considered overweight or obese.

Over the next year, adolescents in the intervention group were given pedometers to encourage walking and running and invited to nutrition workshops and regular exercise sessions during the school day and at lunchtime.

Participation in some of those activities was less than ideal. For example, the girls went to only one-quarter of optional lunchtime exercise sessions, and less than one in ten completed at-home physical activity or nutrition challenges, the researchers reported in the Archives of Pediatrics & Adolescent Medicine.

At the end of the year, girls in both groups had gained a similar amount of weight and there was no difference in their average body fat -- about 33 percent.

The participants also gave similar answers on surveys of how much exercise they got and how much they ate, as well as on measures of self-esteem.

Only "screen time" was significantly lower in the intervention group after a year -- by about half an hour per day.

Preventive medicine researcher Robert Klesges, from the University of Tennessee Health Science Center in Memphis, said that although some anti-obesity programs have helped adults lose weight, the teen population has consistently been a source of frustration for researchers.

"The common belief is: nothing works," he said. "And we've got to get beyond that."

Klesges and his colleagues also found "bupkis" when they tested group behavioral counseling covering physical activity and healthy eating in hopes of preventing obesity in younger African American girls.

"We need to think outside the box," Klesges, who wasn't involved in the new study, told Reuters Health.

That could include learning from what has worked in adult studies, such as giving meal replacement drinks or prepared foods to teens who have trouble making changes to their diet.

Or, it could mean using a "step-care" approach where young people who are still having trouble eating better and losing weight after a few months are given more intensive help -- rather than researchers or their doctor telling them to keep doing the same thing, Klesges said.

SOURCE: bit.ly/KQBh6k Archives of Pediatrics & Adolescent Medicine, online May 7, 2012.

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