Sustained impact of the “Healthy Habits, Healthy Girls – Brazil” school-based randomized controlled trial for adolescents living in low-income communities

Pediatric obesity is a major public health concern in low- and middle-income countries, such as Brazil. There is an urgent need for preventive programs for adolescents and, the assessment of their sustained impact. This paper reports the longer-term (6-month post intervention) effects of the “H3G-Brazil” obesity prevention program on weight status and weight-related behaviors. A cluster randomized controlled trial starting with 10 public schools in the city of São Paulo, Brazil involved 253 adolescent girls [mean (se) age = 15.6 (0.87) years]. Body mass index (BMI), waist circumference (WC), dietary intake, physical activity (PA) and sedentary behaviors (SB) were assessed at baseline, immediate post-intervention and 6-month post-intervention (follow-up). ANCOVA was performed using intention to treat principles. There was no effect on BMI, the primary outcome. Although, meaningful increases occurred in waist circumference for both groups, the intervention group presented a lower increase (F = 3.31, p = 0.04). This effect size, however, was lower than the criterion for small (d = 0.102). Unfortunately, significant results favored the control group for time spent on TV/weekdays (F = 5.13, p = 0.01), TV/weekends (F = 5.46, p = 0.01) and sedentary behaviors/weekdays (F = 5.32, p = 0.04). No other significant results were found. This obesity prevention intervention among Brazilian adolescent girls did not have the desire effect on BMI. The significantly lower increase in waist circumference in the intervention groups is inconsistent with the adverse changes detected in sedentary time.