Objectives: To implement an educational intervention that contributes to the prevention of malnutrition by excess among adolescents. Patients and Method: This descriptive study included a sample of 939 individuals attending school at Colegio Manuel D'Alzon, in Lota (small town), between 2007-2009. Studies included anthropometric evaluations, nutritional intake and training workshops. Parents and teachers were included in the workshops. Healthy nutrition was incorporated in the curriculum, and a site for distribution of healthy foods was implemented. Results: A 3% decrease in prevalence of malnutrition by excess was seen (28% to 25%), most marked among males. This decrease was attributed to reduction in obesity and increase of lower weights. This decrease appears during a period of time when boys show a growth spurt, which occurs earlier among girls. Conclusion: Collaborative interventions between health and education show positive results in this population.