School-based obesity prevention interventions for Chilean children during the past decades: lessons learned

Obesity in Chilean children has increased markedly over the past decades. School-based obesity prevention interventions have been launched by the Ministry of Health and academic groups to tackle this condition. We summarize the main characteristics of the interventions that we have conducted and reflect on the lessons learned. Since 2002, we conducted 1 pilot study, a 2-y controlled intervention including 6- to 12-y-old children (Casablanca), another pilot study, and a 2-y controlled intervention including teachers and their 4- to 9-y-old students (Macul). Both interventions consisted of training teachers to deliver contents on healthy eating, increasing physical education classes, and, additionally in Macul, teachers participated in a wellness program. BMI Z-score and obesity prevalence were compared among children in intervention and control schools by year and among students of intervention and control teachers. In the Casablanca study, the impact was greatest on the younger children during the first school year when the study received the full funding that was required. In Macul, although intervention teachers exhibited improvements in anthropometry and blood measures, the impact on the children was not related to their results. The main lessons learned from these experiences are random allocation of schools, although methodologically desirable, is not always possible; participation of parents is very limited; obesity is not recognized as a problem; and increasing physical activity and implementing training programs for teachers is difficult due to an inflexible curriculum and lack of teachers' time. Unless these barriers are overcome, obesity prevention programs will not produce positive and lasting outcomes.