With approximately a third of teen girls overweight or obese, and the real possibility that they will grow up to be overweight or obese adults, effective interventions are needed. The results of a new study may be onto something that could work.

Researchers with the Kaiser Permanente Center for Health Research found that a program where girls were more motivated by their peers than by their parents was effective. Most other weight loss programs for children and teens typically include family intervention. However, researchers wondered whether parental influence was less important or even counterproductive with teens as they became more independent and more motivated by their peers.

After one year, the girls who took part in the behavioral program with their peers showed slightly lower BMIs than the usual care group, and they had a much better body image and had adopted healthier eating habits.

The study included 208 girls between the ages of 12 and 17 who were all classified as overweight or obese according to standards set by the CDC. The girls were divided into two groups. One group was assigned to a moderately intensive behavioral program, and the other group received usual weight loss advice.

The girls who were in the behavioral program met with their peers and a behavioral counselor on a weekly basis for the first three months of the study; they met every other week during the fourth and sixth month. They were asked to keep a food and exercise diary which they talked about at each meeting.

Throughout the intervention, discussions focused on decreasing portion sizes, making better food and beverage choices, establishing regular meal patterns, increasing intake of fruits and vegetables, and eating more family meals. The behavioral program also stressed exercising five days a week for 30 to 60 minutes, 15 minutes of yoga each day, and decreasing screen time to two hours per day.

Those who were assigned to the usual care group met with their primary care physician at the beginning of the study and received informational materials on weight loss strategies, such as books and a list of online reading about lifestyle changes.

After six months, body mass index (BMI) was calculated on all of the girls, and again six months later. After one year, the girls who took part in the behavioral program with their peers showed slightly lower BMIs than the usual care group, and they had a much better body image and had adopted healthier eating habits. They ate less fast food and consumed more fruits and vegetables.

Though the girls who were in the peer program didn't lose a remarkable amount of weight, this is the first study to show that a weight loss approach designed for teens without parental participation can be effective. Furthermore, the program did not focus on counting calories but on lifestyle changes which may have blunted weight loss to some degree. The researchers hoped that the tools given to the girls in the behavioral program would have more staying power than a program focused on calories.

The study was published online on February 13, 2012 in Pediatrics.