Data analysis
Each outcome was defined based on the corresponding question(s) in the questionnaire. Hence, the healthy food category was defined as fruits and vegetables; unhealthy foods as chips and sugar sweetened beverages (SSB); healthy snacks included fruits while unhealthy snacks included chocolate, cookies, candies, cupcakes, chips, SSB. As for physical activity, the question analysed was ‘do you play or practice activities after school or during weekends, and frequency was recorded as less or more than twice per week’.Categorical variables with multiple categories were recoded as binary when the outcome of interest was adhering to a specific guideline (consuming breakfast daily = 1, other = 0) or in cases of limited observations in certain categories (never consuming chips grouped with less than twice per day = 0). For nutrition knowledge and self-efficacy questions, the computed score from each set of questions reflected overall levels of knowledge and self-efficacy, respectively.Descriptive data at baseline and post-intervention was reported as percentage of children having specific dietary and physical activity behaviours (categorical variables), while means and standard deviations were reported for knowledge and self-efficacy scores. Independent sample t-tests were used to compare intervention and control groups on continuous variables and Pearson’s 