School-based overweight preventive intervention lowers incidence of disordered weight-control behaviors in early adolescent girls.

OBJECTIVE To determine the effect of a school-based intervention to promote healthful nutrition and physical activity on disordered weight-control behaviors (self-induced vomiting or use of laxatives or diet pills to control weight) in early adolescent girls and boys. DESIGN Using a group-randomized, controlled-trial design, we randomly assigned middle schools to an intervention or control condition. Multivariate logistic regression analyses were used to assess the effect of the intervention on the odds of reporting a new case of disordered weight-control behaviors at follow-up, adjusting for sex, school-level prevalence of disordered weight-control behaviors at baseline, and school clusters. Students reporting these behaviors at baseline were excluded from the analyses. SETTING Thirteen middle schools. PARTICIPANTS At baseline, 749 girls and 702 boys in grades 6 and 7. Intervention The 5-2-1 Go! intervention (Planet Health obesity prevention curriculum plus School Health Index for Physical Activity and Healthy Eating: A Self-Assessment and Planning Guide, Middle/High School Version) was implemented during 2 school years, from November 2002 through May 2004. Main Outcome Measure Self-reported disordered weight-control behaviors in last 30 days at follow-up. RESULTS At follow-up in girls, 3.6% (15 of 422) in control schools compared with 1.2% (4 of 327) in intervention schools reported engaging in disordered weight-control behaviors (P = .04). Multivariate analyses indicated that the odds of these behaviors in girls in intervention schools were reduced by two thirds compared with girls in control schools (odds ratio, 0.33; 95% confidence interval, 0.11-0.97). No intervention effect was observed in boys. CONCLUSIONS Results add compelling support for the effectiveness of an interdisciplinary, school-based obesity prevention intervention to prevent disordered weight-control behaviors in early adolescent girls.