Effect of a Community-Based Program on Preschoolers' Physical Activity and Nutrition in Chile.

Introduction: Childhood obesity has reached critical levels in Chile, particularly among preschoolers from low-income families who face barriers to nutritious food and physical activity. Early interventions are essential to mitigate long-term health risks. This study evaluates the Chile Active Intervention, a community-based program promoting physical activity and healthy eating among preschoolers attending public daycare centers in Antofagasta, Santiago, and Temuco. Objective: To assess the effectiveness of a structured intervention in improving physical activity levels, dietary habits, and obesity-related risk factors in children aged 3 to 5 years old. Methods: A quasi-experimental design was implemented with intervention and control groups, including 1204 children from public daycare centers. The intervention-comprised educator training on healthy eating structured physical activity sessions tailored for young children and family engagement through "Healthy Days" events. Pre- and post-intervention assessments measured anthropometric variables, body composition, physical activity, and dietary intake. Results: The intervention led to positive changes in weight-for-height Z-scores, body fat percentage, and skinfold thickness, particularly among high-risk children. Physical activity assessments showed reduced sedentary time and increased active play. Dietary improvements included higher fruit and vegetable consumption and reduced ultra-processed food intake. Conclusions: This study demonstrates that early, community-based interventions can effectively improve health behaviors in preschoolers. The program's scalability across Chile is promising, with parental involvement and institutional support being key to sustaining impact. Long-term evaluations are recommended to assess its lasting effects on childhood health outcomes.