Healthy diet and physical activity have consistently been found to be positively correlated; however, most health behavior theories are focused on regulation of changes in single, rather than multiple, behaviors. Thus, this study explored the mechanism of the carry-over effect between diet and physical activity by conducting a longitudinal study with 706 participants to test the bottom-up and top-down hypotheses of hierarchical self-efficacy (SE). At Time 1 (baseline) and Time 3 (4 weeks after baseline), dietary behavior, physical activity, and self-efficacies of these behaviors (at the contextual level) were measured, while at Time 2 (2 weeks after baseline), general SE (at the general level) was assessed. Mediation analysis and structural equation models supported both the bottom-up and top-down hypotheses for different levels of self-efficacies, suggesting that hierarchical SE is an important factor underlying the carry-over mechanism between diet and physical activity.
Keywords: Carry-over effect; diet; physical activity; self-efficacy.