Effectiveness of a school-based obesity prevention program on the BMI Z-score and body fat at 6 months in Mexican children: study protocol of a cluster randomized controlled trial

School-based obesity prevention programs show positive effects on obesity and lifestyle parameters. However, the most efficient way of implementing them is unknown. In Mexico, available studies present methodological limitations. The aim of this study is to evaluate the feasibility and effectiveness of a school-based obesity prevention program 1) implemented by advanced undergraduate nutrition and physical activity students, and 2) the same program implemented by schoolteachers and advanced undergraduate physical activity students, each compared to a control group of Mexican children. This study is a cluster randomized controlled trial. Children from several schools in Hermosillo, Sonora, Mexico will be invited to participate. The schools will be randomly assigned to one option: 1) the Planet Nutrition Program (PNP) delivered by advanced undergraduate nutrition and physical activity students, 2) PNP by schoolteachers, or 3) a control group. The intervention will consist of nutritional education and physical activity sessions for children and nutrition information for parents. The BMI Z-score, body fat, and lifestyle parameters will be evaluated at baseline and at 6 months. If successful, we expect that the program turns out a model for obesity prevention in this age group, with a potential for dissemination in Mexican schools.