Investigating the effect of theory-based educational intervention on enhancing physical activity and reducing weight among overweight and obese students

Overweight and obesity among adolescents pose significant public health challenges worldwide, increasing the risk of chronic diseases and psychological problems. Promoting physical activity is a key preventive strategy, yet many adolescents do not meet recommended activity levels. The Theory of Planned Behavior (TPB) provides a useful framework for designing educational interventions to modify health behaviors.

This study aimed to investigate the effect of a TPB-based educational intervention on enhancing physical activity and reducing weight among overweight and obese high school students in Fasa city, Iran. A quasi-experimental study was conducted on 240 high school students randomly assigned to intervention (n = 120) and control (n = 120) groups. Data were collected using a structured, self-administered questionnaire that included demographic information, constructs of the Theory of Planned Behavior (knowledge, attitude, subjective norms, perceived behavioral control, and behavioral intention), and the short-form International Physical Activity Questionnaire (IPAQ) to assess physical activity levels.

Anthropometric measurements (weight, height, and BMI) were recorded before and four months after the intervention. The intervention consisted of eight interactive educational sessions designed according to TPB constructs, employing lectures, group discussions, visual materials, and physical activities. Data analysis was performed using chi-square, independent t-tests, and paired t-tests, with statistical significance set at p 0.05).

Mean pre-intervention BMI was 26.3 ± 8.7 kg/m², and average physical activity was about 380 MET-min/week. Four months after the intervention, the intervention group showed significant increases in knowledge, attitude, subjective norms, perceived behavioral control, behavioral intention, and physical activity levels (p