Application of Theory of Planned Behavior to Improve ObesityPreventive Lifestyle among Students: A School-based Interventional Study

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.