To be eligible for the review, studies had to evaluate a school-based intervention for the prevention of obesity targeting the general population of children. Studies had to report change in body mass index (BMI) as an outcome. Inclusion criteria for study designs were not reported, but all the included studies had a no-intervention control group. Studies had to be conducted in USA or UK (most included studies were in USA).
Interventions in included studies were diverse and included education, physical activity, playground markings, provision of fruit, diet, provision of filtered water, "new moves" and reduction of carbonated drink intake. Intervention duration ranged from three months to three years. Follow-up duration ranged from three to 12 months (one study had annual follow-ups, but it was not reported how many of these were done). Baseline BMI ranged from approximately 17.5 to 26.5.
The authors did not state how studies were selected for the review.