School-Based Obesity Prevention Intervention in Chilean Children: Effective in Controlling, but not Reducing Obesity

Objective. To evaluate the effectiveness of a 12-month multicomponent obesity prevention intervention.Setting. 9 elementary schools in Santiago, Chile.Subjects. 6–8 y old low-income children (N=1474).Design. Randomized controlled study; 5 intervention/4 control schools. We trained teachers to deliver nutrition contents and improve the quality of PE classes. We determined % healthy snacks brought from home, children’s nutrition knowledge, nutritional status, duration of PE classes, and % time in moderate/vigorous activity (MVA). Effectiveness was determined by comparingΔBMIZbetween intervention and control children using PROCMIXED.Results. % obesity increased in boys from both types of schools and in girls from control schools, while decreasing in girls from intervention schools (all nonsignificant). % class time in MVA declined (24.5–16.2) while remaining unchanged (24.8–23.7%) in classes conducted by untrained and trained teachers, respectively. In boys, BMIZdeclined (1.33–1.24) and increased (1.22–1.35) in intervention and control schools, respectively. In girls, BMIZremained unchanged in intervention schools, while increasing significantly in control schools (0.91–1.06,P=0.024). Interaction group*time was significant for boys (P<0.0001) and girls (P=0.004).Conclusions. This intervention was effective in controlling obesity, but not preventing it. Even though impact was small, results showed that when no intervention is implemented, obesity increases.