The predictive power of the Health Action Process Approach (HAPA) in a weight-loss trial

Background:This correlational study examined the value of the HAPA theory at predicting weight-loss in a weight-loss trial.

Methods:Participants (N¼22) undergoing an 8-week weight-loss programme were recruited from aprivate hospital. Baseline questionnaires measured demographics, height, weight, self-efficacy,risk-perception, outcome-expectancies and intentions.

Findings:Questionnaires at 4 and 8 weeks measured weight-loss behaviours – physical activity,dietary variables, effort and weight. The HAPA was able to significantly predict weight-loss(RAˆ2¼0.57,p¼0.027). Self-efficacy and risk-perceptions were significantly related to intention(r¼0.80,p50.001 andr¼�0.48,p50.01 respectively). Intentions were significantly related to weight-loss behaviour was significantly related toweight-loss (r¼0.73,p50.01). The study provides evidence for the predictive value of the HAPAat predicting weight-loss.

Discussion:Findings build on current knowledge of the cognitions and behaviours involved insuccessful weight-loss and may contribute to the development of interventions designed to increaseweight-loss in the overweight and clinically obese population.