[Impact of an intervention on diet and physical activity on obesity prevalence in schoolchildren]

In Chile childhood obesity is a growing public health problem. Intervention programs within schools have shown variable results, with better impacts when multiple aspects are involved and included the entire educational community. The objective of the study was to evaluate the effect on the nutritional status of children in intervention schools within 2 years of duration (Healthy Living Program). The sample included 2,527 students first through fourth grade of 3 counties of Santiago. The students were intervened and followed for a period of two years in their food and nutrition habits, physical activity and self-care practices, by a team of nutritionists and physical education teachers. Weight and height were measured at start of program, end of the first and second years of intervention, under standardized conditions and calculated the Z score of BMI and nutritional status according to the WHO reference 2007. At the end of the second year 1,453 children were reassessed. There was a significant decrease in BMI Z score in obese children (-0.3 SD) and obesity decreased from 21.8% to 18.4% at the end of the intervention. 75% of schoolchildren obese and 60.5% overweight decreased their BMI Z score, reduction that was greater in men and students in the upper grades. 51.9% of normal weight children increased their BMI Z-score age, although most less than 0.5 SD. The intervention in education, nutrition and physical activity among schoolchildren in three communes of Greater Santiago was effective in reducing the prevalence of obesity (-3.4 percentage points). The big challenge is to find mechanisms to give continuity to the program and evaluate long-term effects.