Snack food consumption among young people. The role of habit in the Theory of Planned Behavior

This study aimed to test the validity of a relation model for the prediction of both intentions and behaviors to eat fresh fruit as snack food between meals. The model was based on the Theory of Planned Behavior (TPB; Ajzen, 1991), to which a measure of ‘habit’ was added as a further predictor. Habit is defined as a learned and automatic response to specific stimuli, and has been detected by a short form of the Self-Report Habit Index (Verplanken & Orbell, 2003). Moreover, the Body Mass Index (BMI) was considered as a control measure. Data collection was performed through a two-wave design – with a 15-days’ time lag –, thanks to anonymous self-administered structured questionnaires. At T1, TPB constructs along with the habit of consuming fresh fruit as snack food, socio-demographic variables and BMI were assessed. At T2, only self-reported actual consumption of fresh fruit as snack was measured. A group of 202 students from the University of Padua took part in the research (88% women; mean age 21 years old). Data were analyzed by means of hierarchical multiple regression. In sum, while the predictive power of the TPB received support, the introduction of habit significantly improved the percentage of explained variance by 16% in the case of intention, and by 5% in the case of behavior. Overall, the TPB-extended model explained 67% of the intention variance and 57% of that of behavior. In conclusion, the results support both the usefulness of TPB in predicting healthy eating behaviors, and in designing interventions aimed at promoting healthy eating habits.