Design of a school randomized trial for nudging students towards healthy diet and physical activity to prevent obesity: PAAPAS Nudge study protocol

OBJECTIVE: To evaluate the effectiveness of nudge activities at school on the students’ body mass index (BMI). DESIGN: School-based factorial randomized community trial. SETTING: Eighteen public schools in the municipality of Duque de Caxias, metropolitan area of Rio de Janeiro, Brazil. PARTICIPANTS AND INTERVENTION: The 18 schools will be randomized into 4 group arms: group 1—control (without any activity); group 2—will receive educational activities in the classroom; group 3—will receive changes in the school environment (nudge strategies); group 4—will receive educational activities and changes in the school environment. Activities will occur during the 2018 school-year. MAIN OUTCOME MEASURE(S): The primary (BMI) and secondary (body fat percentage) outcomes will be assessed at baseline and after the study using a portable electronic scale with a segmental body composition monitor. The height will be measured by a portable stadiometer. ANALYSIS: Statistical analyses for each outcome will be conducted through linear mixed models that took into account the missing data and cluster effect of the schools.