Chi-squared test will be used to analyze the association between independent qualitative variables, along with the McNemar test for paired samples. The Student t-test will be used for the comparison of means between two groups, and the paired t-test will be applied to assess changes within one same group. Alternatively, the corresponding nonparametric tests will be used, as required. The relationship between quantitative variables will be analyzed using Pearson's correlation coefficient or Spearman coefficient in the case of asymmetrically distributed variables. Multivariate linear regression analysis and logistic regression analysis will be used to analyze the variables determining the changes in physical activity and eating and sleeping habits. In order to analyze the effect of the intervention, comparison will be made of the changes observed in the comparison group (CG) versus the intervention group (IG), with estimation of the Cohen d statistic, adjusting for the variables that may influence the results. A multilevel analysis will be performed to determine the effect of the different pilot sites or schools. The effect of the intervention could be modified by gender, cultural and socioeconomic level, body mass index (BMI), as well as by the baseline lifestyles, which will be controlled in the analysis. Separate analyses will also be performed for females, males, low and high socio-economic level to assess the effect of the intervention in these categories of interest. The level of statistical significance will be set at α=0.05 and all tests will be two-tailed. Statistical analyses will be carried out using the software packages SPSS, version 22.0 (SPSS Inc, Chicago, IL) and Stata (StataCorp. 2009. Stata Statistical Software: Release 11. College Station, TX: StataCorp LP). Conversational methods will be used to collect data in focus groups. All of them will be audio and/or videotaped and transcribed systematically, literally, and anonymously. An analysis will be made of thematic content, coding the data and grouping them into predefined categories based on topics. The analysis will be done with the support of Atlas.Ti and by triangulation of analyst.