Background Nowadays childhood obesity has become one the most challenging issue which is considered as a principle public health problem all around the world. This study was conducted with the aim of evaluating the impact of a 7-month school-based nutrition education intervention using social cognitive theory (SCT) to prevent obesity among overweight and obese adolescent girls. Method In this cluster randomized community trial after choosing schools, a total of 172 overweight and obese girl students participated in the study (87 in the intervention and 85 in the control group). A 7-month intervention based on SCT for students, their parents, and teachers was conducted. At baseline and end of the study, body mass index (BMI), waist circumstances (WCs), dietary intake, and psychological questionnaires regarding the SCT constructs were obtained. Results After 7 months, the mean of BMI and WCs reduced in the intervention group from 29.47 (4.05) to 28.5 (4.35) and from 89.65 (8.15) to 86.54 (9.76), respectively, but in comparison to the control group, they were not statistically significant ( p values .127 and .504, respectively). In the intervention group, nutritional behaviors and most of the psychological variables (self-efficacy, social support, intention, and situation) were improved in favor of the study and they were significant in comparison to the control group ( p < .05). Conclusion Although school-based nutrition education intervention using SCT did not change significantly BMI and WCs among the targeted population in this study, dietary habits as well as psychological factors improved significantly in the intervention group. This trial was registered in Iranian Registry of Clinical Trials, www.irct.ir (IRCT2013103115211N1).
Keywords: Iran; adolescents; nutritional behaviors; obesity; social cognitive theory.