1 Associate professor, Social Determinants of Health Research Center, Department of Public Health, School of Health, Urmia University of Medical Sciences, Urmia, Iran

2 PhD Student, Department of Health Education and Promotion, School of Health, Isfahan University of Medical Sciences, Isfahan, Iran.

3 Associate Professor, Department of Biostatistics and Epidemiology, School of Medicine, Urmia University of Medical Sciences, Urmia, Iran

4 Associate Professor Of Psychology, Department of Psychiatry, Faculty of Medicine,Urmia University of Medical Sciences, Urmia, Iran.


Background: Obesity is regarded as the epidemic of diseases correlated with an unhealthy lifestyle. The avoidance of inactivity could prevent obesity and its relevant issues. The present study aimed to explore the effectiveness of the theory of planned behavior (TPB) to improve obesity-preventive lifestyle among Iranian students.
Materials and Methods: The current study was a quasi-experimental study. Using multistage sampling, 100 Junior High-school students in Khoy, Iran in 2016 were selected and assigned to two groups, namely intervention (n=50) and control (n=50). To collect the study data, researchers utilized a researcher-made questionnaire including items about demographic information and TPB constructs such as attitudes, subjective norms, perceived behavioral control (PBC), behavioral intention, and behaviors related to physical activities, television watching, and computer-game playing. The data were analyzed using SPSS software version 20.0.
Results: The mean age of the intervention group was 13.88 ± 0.79 and that of the control group was 14.12 ± 0.77 years. Prior to the intervention, there was no significant difference between the two groups in the mean of the scores of both the TPB constructs and their health performances. However, three months after the intervention, the mean score of attitudes, subjective norms, perceived behavioral control and behavior of students changed, and all these changes were statistically significant between two groups (p<0.05).
Conclusion: The results of the study showed that the TPB could be an appropriate theoretical basis for designing and evaluating interventions to encourage people to avoid a sedentary lifestyle and inactivity.