[Evaluation of an obesity prevention intervention which included nutrition education and physical activity applied in public schools of Santiago, Chile]. / Evaluación de una intervención en educación alimentaria y actividad física para prevenir obesidad infantil en escuelas públicas de Santiago de Chile.

The main objective of this study was to assess the effectiveness of an obesity prevention intervention which included nutrition education and physical activity applied to low income Chilean children in a longitudinal three-year follow-up study. Participants included all 4-7 year old children from 7 public schools located in a low socioeconomic district of Santiago. The main aspects of the intervention were: training of teachers so they could apply an educational program on healthy eating, increase in physical education classes from 3 to 4 per week, and improvement of their quality. Weight, height, waist circumference (WC) and the 6-minute walk distance (6MWD) were assessed yearly in 597 children. We calculated BMI, BMI Z, % normal (N), overweight (OW) and obesity (OB), WC > 90th percentile (NHANES III) and fitness (6MWD/height). Annual changes in BMI Z, WC, 6MWD and fitness were assessed, using repeated measures ANOVA and the test of proportions. Knowledge in healthy eating was assessed during 2 of the 3 years. Results showed that % OB remained unchanged for 2 years (17%) but increased to 19.3% at follow-up. BMI Z increased from 0.3 to 0.38 (p = 0.052) in the N, remained unchanged in the OW, while decreasing significantly in the OB (2.73 to 2.41 p < 0.0001). % WC > 90 th percentile decreased in the OW and OB; 6 MWD was higher in the OW, but the increase in distance overtime was greater among the N. Overall fitness improved, however it was only significant among the N (p = 0.0002). There was a significant increase in food knowledge. We conclude that in spite of a decrease in BMI Z of the OB, an improvement in fitness in the N and food knowledge in all the children, obesity increased at follow-up. This study shows that in school-based obesity programs it is necessary to apply more intense interventions with another type of methodology; otherwise this condition will continue to rise.