Efficacy of a school-based physical activity and nutrition intervention on child weight status: Findings from a cluster randomized controlled trial

Despite the benefits of factorial designs in quantifying the relative benefits of different school-based approaches to prevent unhealthy weight gain among students, few have been undertaken. The aims of this 2 x 2 cluster randomized factorial trial was to evaluate the impact of a physical activity and nutrition intervention on child weight status and quality of life. Twelve primary schools in New South Wales, Australia randomly allocated to one of four groups: (i.) physical activity (150 min of planned in-school physical activity); (ii.) nutrition (a healthy school lunch-box); (iii.) combined physical activity and nutrition; or (iv.) control. Outcome data assessing child weight and quality of life were collected at baseline and 9-months post-baseline. Within Grades 4-6 in participating schools, 742 students participated in anthropometric measurements, including child body mass index (BMI) and waist circumference, at baseline and follow-up. Findings indicated that students that received the nutrition intervention had higher odds of being classified in the BMI category of underweight/healthy weight (OR 1.64 95%CI 1.07, 2.50; p = 0.0220), while those who received the physical activity intervention reported a lower waist circumference (mean difference -1.86 95%CI-3.55,-0.18; p = 0.030). There were no significant effects of the nutrition or physical activity intervention on child BMI scores or child quality of life, and no significant synergistic effects of the two interventions combined. Future research assessing the longer-term impact of both intervention strategies, alone and combined, is warranted to better understand their potential impact on child health.