The evolving evidence on obesity in children

You have, no doubt, heard the statistics about youth and obesity: Approximately 12 million American youth are obese; that is 17 percent of people ages 2 to19. Youth who are obese are more likely to live in low-income neighborhoods, and are more likely to be black, Hispanic, or native American.  And we hear all sorts of reasons why young people gain weight such as too may sugary drinks, less physical activity and a lack of access to healthy foods.

The question is, what can we do about it? The Cochrane Collaboration has published a series of systematic reviews about a wide range of obesity interventions for young people. Last month, the Collaboration released its final two analyses, which looked at the data on lifestyle interventions for weight loss aimed at children ages 6 to 11 and youth ages 12 to 17. (Earlier reviews in the series looked at lifestyle interventions for preschool kids, interventions for parents, obesity surgery in youth and pharmaceutical products.)

In all, that’s a lot of data about helping kids lose weight. Here are some of the most compelling take-home messages:

Lifestyle interventions

For youth in preschool through high school, lifestyle interventions led to small but significant improvements in weight and body mass index, or BMI. (BMI is a measurement of body fat related to height.)

For preschool-aged kids, the most successful interventions included components of diet and physical activity, as well as educational or coaching sessions for the parents or the entire family. In studies that measured outcomes over the long-term, children who participated were able to sustain their improvements over several years.

For children ages 6 to 11, intervention programs encouraged children to eat healthy foods, become more active, and spend less time watching TV. The interventions were delivered in schools, health care settings and community settings, and parents were typically involved. The evidence found that programs delivered at each of these locations were equally successful.

For teenagers, the interventions focused on diet, activity, and behavioral coaching. In addition to weight-loss, the review found small improvements for teens in “health-related quality of life,” a measure of a person’s satisfaction with their life and health. For studies conducted over longer periods of time, participants saw greater reductions in body mass, a sign that this type of program can work over the long-term.

A separate analysis found no substantial weight-loss for children whose parents participated in parents-only interventions, but the evidence was limited—a sign that future studies could identify them as an effective option.

Medical interventions

There is less evidence available for medical weight-loss interventions for youth. Researchers found only one high-quality study that evaluated weight-loss surgery for Australian youth ages 14 to 18. In the study, 25 participants underwent gastric banding surgery and 25 others participated in a lifestyle intervention that included diet modification, exercise and behavioral coaching.

Youth who underwent surgery lost an average of 76 pounds, but nearly half of them experienced adverse events and more than 25 percent required a second surgery. Youth in the lifestyle intervention group lost an average of 6 pounds with no adverse events. The authors conclude that the study did not provide enough information to recommend weight-loss surgery as an effective intervention for youth.

A separate analysis looked at pharmaceutical interventions for obese youth. Researchers found 21 randomized-controlled trials that compared youth taking a variety of weight-loss drugs to lifestyle interventions to help youth lose weight. On the whole, youth who took the medicines experienced small but significant weight loss. But nearly a quarter of participants dropped out of these studies.

In addition, many of the drugs have never been officially approved for youth, and several have been withdrawn from the market due to adverse events. Overall, researchers found the quality of evidence for pharmaceutical interventions was low, and more data are needed to make strong recommendations.

After carefully reviewing all six analyses, the take-home message is that lifestyle interventions can help obese youth to lose weight. While medical interventions lead to some improvements, there is less evidence that they are effective across broad populations, and they are inherently more risky.

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