Long-term Effect of an Excess-Weight-Reduction Intervention among Iranian School Children: A 13-month Follow-up of a Cluster Randomized Controlled Trial

Childhood obesity and overweight have become major public health problems worldwide. To combat this problem, effective, sustainable, and consistent strategies are needed. In this study, the long-term effect of a school-based intervention for weight reduction was evaluated in primary school students in Tehran, Iran.

This was a cluster randomized controlled trial (RCT) conducted in 12 primary schools in a low- to middle-class district in Tehran, Iran. The participants were 334 overweight or obese primary school students (girls =164) based on World Health Organization standards, equally distributed in the intervention (n=167) and comparison (n=167) groups. It was a multi-component intervention and included nutrition education and increased physical activity (PA), a lifestyle modification program for parents, and changing the food items sold in canteens of the schools. Body mass index Z-score [BMI-Z] was determined as the primary outcome and measured at baseline, three months after baseline, at post-test (after 18 weeks), and follow-up (13-month). In total, 205 students (59.5%) completed the follow-up. Analyses were carried out based on the intention-to-treat principle using linear mixed models.

After 13 months, the BMI Z-score decreased in both intervention and comparison groups. However, the change was more significantly observed in the intervention group (adjusted change: 0.098, 95% CI: (0.03-0.16) compared with comparison group (P=0.003(. The intervention had a more significant effect on BMI Z-score among girls (adjusted change: 0.36, 95% CI: (0.27-0.45) compared with the comparison group (P<0.001)( than among boys (adjusted change: -0.14, 95% CI: (-0.23- -0.05) compared with the comparison group (P=0.002).

The intervention was an effective way to reduce BMI in the girls and the effect lasted for a relatively long time.