The Effect of Education on Reducing Fast Food Consumption in Obese Iranian Female Adolescents: An Application of the Transtheoretical Model and the Theory of Planned Behaviour

Background The number of reported food illnesses in Iran has increased over the past 10 years. Objectives The present study aimed at investigating the effect of education, based on the transtheoretical model (TTM) and the theory of planned behaviour (subjective norm and perceived behavioural control), on reducing fast food consumption in obese Iranian female adolescents. Methods In this quasi-experimental study, data were collected through a survey. This study included 420 obese Iranian female adolescents, aged 15 to 18 years, who were gathered from 12 schools in city of Sabzevar in Iran during 2014 tand 2016. Using a questionnaire, the demographic and anthropometric characteristics, transtheoretical model (TTM) constructs, subjective norm, and perceived behavioural control were measured and analysed. Results The average rates of perceived behavioral control (11.949 ± 2.876), subjective norms (16.515 ± 4.877), stages of change (6.355 ± 1.342), processes of change (8.614 ± 3.406), and self-efficacy (22.447 ± 6.783) in the education group were meaningfully increased (P value < 0.05); however, these changes were not meaningful in the control group (P value > 0.05). Also, no statistically meaningful difference was obtained in decisional balance between the 2 groups after the intervention (P = 0/924). Conclusions The results of this study suggest that the use of TTM (except with decisional balance) focuses on the perceived behavioural control, and subjective norms can be used in educational interventions and have useful results.