Effectiveness of a School-based Obesity Prevention Program on Body Fat At 6 Months of Mexican Children

School-based programs are an essential strategy for preventing obesity, yet the most effective way to implement them remains unclear. This study aims to evaluate the effectiveness of a school-based obesity prevention program, delivered by different implementers, in comparison to a control group, focusing on body fat reduction in Mexican children. This is a cluster randomized controlled trial. Approximately six public elementary schools (240 children) in Hermosillo, Mexico, will be invited to participate. Schools will be randomly assigned to one of three groups: a program implemented by advanced undergraduate students in Nutrition and Physical Activity (NUT-PA), a program implemented by Physical Education teachers and Physical Activity students (PEST-PA), or a control group. The intervention will consist of a 6-month obesity prevention program that includes nutrition education, physical activity sessions, and parent participation. The control group will continue with their regular school activities. The primary outcome will be the difference in body fat percentage at 6 months between the NUT-PA group and the control group, as well as between the PEST-PA group and the control group. Secondary outcomes will include BMI Z-score, waist circumference, and various lifestyle parameters. A mixed-effects linear analysis will be conducted using an intention-to-treat approach.