Effect of intervention on total and central obesity in students: the Saúde na Boa project

Although studies have shown that the school setting is favorable for preventing obesity, relatively few studies have examined weight-gain prevention in youths. To assess the effectiveness of a nine-month intervention to reduce total and central obesity in youths attending night secondary school in two Brazilian state capitals (Florianópolis and Recife). This was a randomized controlled intervention study conducted from March to December 2006. The indicators of obesity assessed were the body mass index (BMI), waist circumference (WC) and waist-to-height ratio (WHtR). Statistical analysis was performed using the chi-square and McNemar's tests. A total of 2,155 participants were assessed at baseline, and 989 participants were assessed after the end of the intervention. In the intervention group, the frequency of total obesity, as assessed by the BMI (baseline: 3.8%; after intervention: 4.3%), and of central obesity, as assessed by the WHtR (baseline: 9.5%; after intervention: 10.4%), stabilized after nine months. However, the frequency of central obesity, as assessed by the WC, increased in the intention-to-treat analysis (baseline: 5.4%; after intervention: 7.9%). In the control group, the frequency of total obesity (baseline: 3.8%; after intervention: 4.7%) and central obesity, as assessed by both WHtR (baseline: 8.1%; after intervention: 9.7%) and WC (baseline: 6.1%; after intervention: 8.2%), increased. The intervention implemented by the Saúde na Boa project helped to stabilize the prevalence of total and central obesity in the investigated population.