Unhealthy dietary habits and physical inactivity are among the leading causes of preventable death and illness in the United States (Behavioral Risk Factor Surveillance System, 2008; McGinnis & Foege, 2004; Mokdad, Marks, Stroup, & Gerberding, 2000). The current study applied the Theory of Planned Behavior (TPB; Ajzen, 1991) to predict prevalent preventive and risky weight-related behaviors, including exercise, fruit and vegetable intake, fasting, and binge eating, in a nonclinical sample. The TPB model was expanded to include additional cognitive and affective variables that strengthened the prediction of risky, more extreme weight-related behaviors. The study assessed the behavioral intentions of 161 undergraduate students, 135 of whom reported subsequent behavior in a testing session held two weeks later.
Overall, the effectiveness of the TPB was supported in the prediction of intentions to perform preventive weight-related behaviors. The traditional TPB model was only partially supported in the prediction of intentions to engage in risky eating behaviors. Additionally, dysfunctional weight-related cognitions predicted intentions to fast and anticipated affective reaction predicted intention to binge eat above and beyond variance accounted for by the TPB variables. Intention, past behavior, and dysfunctional weight-related cognitions were associated with future binge eating and fasting, but only past behavior significantly predicted future exercise and fruit and vegetable intake. The exploration of specific eating disordered cognitions related to risky eating behaviors in future studies using community and clinical samples may contribute to the development of more effective preventative campaigns, interventional strategies, and at-risk detection. The use of an extended TPB model may also be applied in future, interventional studies to assess the causal role of cognitive distortions in risky weight-related behaviors and to further our understanding of eating disordered behaviors.
