Evaluation of an obesity prevention program in adolescents of public schools.

OBJECTIVE To evaluate the effects of an obesity prevention program on the dietary practices of public school adolescents. METHODS An intervention was conducted with 331 students aged between 11 and 17 years, enrolled in the 5th and 6th grades of two state public schools in the city of Niterói, Southeastern Brazil, in 2005. These schools were categorized into "intervention schools" (IS) and "control schools" (CS) for comparison. Dietary practices were analyzed using self-administered questionnaires before and after the intervention period: fast food consumption; soft drink consumption; replacement of meals for snacks; consumption of fruits and vegetables; and type of food consumed during school breaks. Chi-square test and McNemar's test were applied to compare proportions, considering a value of p <0.05. RESULTS In the baseline, 185 students participated in the IS (82.2% of those eligible) and 146 students participated in the CS (70.5% of those eligible). In the post-intervention phase, there was a loss of 10.3% of IS adolescents and 27.4% of CS ones. There were no significant changes in dietary practices in CS. In contrast, IS showed an increase in the proportion of students who reported not consuming snacks sold by street vendors (from 36.7% to 50.6%; p = 0.02) and adolescents who reported not replacing their lunch (from 44.5% to 65.2%; p<0.01) and dinner (from 38.4% to 54.3%; p<0.01) for snacks. The main favorable change was the reduction in the frequency of consumption of fast food snacks in IS, when compared to CS (from 72.7% to 54.4%; p = 0.001). CONCLUSIONS Favorable changes in the adolescents' dietary practices were found and they encourage the implementation of programs of this nature. However, long-lasting interventions need to be implemented and evaluated in terms of their effectiveness.