Introduction: the prevalence of unhealthy weight control behaviors in adolescents is increasing and unhealthy weight control behaviors can have serious physical and mental consequences in adolescents. The aim of this study was to determine the effect of education based on Health Belief Model on the prevention of unhealthy weight control behaviors in female adolescents aged 13-15 year.

Methods: This was a quasi-experimental study conducted on 160 girls in high schools of Karaj city. Sampling was performed in two stages: in the first stage, schools were randomly selected and assigned to two groups. In the second phase, samples, based on the entry criteria, were selected by convenience sampling. Data for pre-test were collected using a questionnaire in both groups. The experimental group received the educational intervention in the form of presentations in four sessions, conducted along with questions and answers. Eight weeks after the educational intervention, post-test was given to both groups and data were analyzed before and after the training using SPSS software and Fisher's exact test, chi-squared and independent and dependent t-tests.

Results: In comparison of the mean score of Health Belief Model parts (perceived susceptibility, perceived severity, perceived benefits, perceived barriers, guide to action, and preventive behaviors) between the intervention and control groups, there was a significant difference between before and after the intervention (P < 0.001).

Conclusions: The results of this study showed that educational interventions based on Health Belief Model can be effective in preventing unhealthy weight control in adolescents. On this basis, it is suggested to run trainings in order for the prevention of unhealthy weight control behaviors based on Health Belief Model for young people and in schools.