Objective. To determine the impact of the educational-motivational intervention “Como jugando” on the body mass index (BMI), knowledge on nutrition, physical activity levels, and eating patterns in students from the first to fourth grades of four educational institutions (EIs) of Cercado de Lima after the first year of the intervention. Materials and methods. This was a quasi-experimental, controlled study. BMI, knowledge on nutrition, frequency of food consumption, and level of physical activity were evaluated. The “Como jugando” program included playful and experiential activities for school children and involved both teachers and parents. The impact was estimated by applying the McNemar test for related samples and regression models for the analysis of differences in adjusted variables related to children and their mothers. Results. The study included 696 school children from two experimental EIs and two control EIs. The Z-score for BMI and the prevalence of obesity did not vary during the study period. The intervention improved the knowledge of nutrition [odds ratio (OR): 1.46; 95% confidence interval (CI): 1.17–1.81], reduced the likelihood of poor levels of physical activity (OR: 0.63; 95% CI: 0.46–0.87), and improved the consumption patterns for all food categories except vegetables in the intervention group. Conclusions. The “Como jugando” intervention, in the first year of implementation, did not reduce the Z-score for BMI but improved the knowledge of nutrition, reduced the probability of poor levels of physical activity, and maintained or increased the consumption of fruits, sugar-free water, packaged juices, and sweet and savory cookies. Therefore, the “Como jugando” intervention should be better studied in order to estimate its impact on biological indicators.