Abstract
Background: The purpose of this study was to evaluate the effect of HealthCorps, a high school peer mentoring program, on youth diet, physical activity, health knowledge, BMI, and percent body fat. Methods: This study had a quasi-experimental nonrandomized design with 6 intervention schools and 5 control schools. The estimation sample consisted of 971 high school students (511 intervention, 460 control). The intervention lasted for one semester and consisted of specially trained recent college graduates serving as peer mentors to teach nutrition and promote physical activity. Outcome measures included self-reported diet and physical activity, health knowledge, and measured BMI and percent body fat. Difference-in-differences models were estimated, controlling for student characteristics including age, gender, grade, and ethnicity. Results: HealthCorps was associated with a reduction in self-reported consumption of soda pop of 0.61 times per week (p = 0.04), or 13.0%. This beneficial effect was concentrated among girls, among whom the HealthCorps program lowers soda pop consumption by 1.12 times per week (p < 0.01), or 25.7%. The above estimates were based conservatively on the assumption of zero benefit for dropouts; excluding dropouts from the analysis resulted in larger effect sizes, including the result that students who participated in HealthCorps were 45% more likely to report that they were more physically active now than they were last year (p = 0.05). Conclusions: HealthCorps is effective in reducing soda pop consumption, in particular among girls. In general, peer mentoring holds promise for improving youth diet and physical activity behaviors.