A systematic review to determine the effectiveness of interventions designed to prevent overweight and obesity in pre-adolescent girls.

Childhood overweight/obesity is recognized as an increasing health problem. The objective of this review was to determine the effectiveness of interventions designed to prevent overweight and obesity in pre-adolescent girls. The papers included were those studying children (must include results for girls) from within the 7-11 years age range from any country and ethnic background. The included interventions lasted at least 12 weeks and modified a combination of nutrition, physical activity, knowledge, attitudes or health-related behaviours associated with the development of childhood overweight and obesity. Effect sizes were calculated where possible using Cohen's classifications of small (0.2-0.5), medium (0.5-0.8) and large (>0.8) effect sizes. Thirty studies met the inclusion criteria of which four were cluster randomized controlled trials, 14 were randomized controlled trials, 11 were controlled trials and one was a cohort pre-post trial. There were four weak, 11 moderate and 15 strong quality studies. Eleven studies were considered short term and 19 long term (≥12 months). There were 66 effect sizes less than 0.2, 56 categorized as low, 16 as medium and two as high. There is the potential for interventions aimed at pre-adolescent girls to reduce the risk factors associated with childhood overweight and obesity, although the sustainability of the effects of such interventions is less clear.