Objectives: Unhealthy diet and physical inactivity are main causes of many diseases and hence, the development of effective interventions is warranted. However, targeting both health behaviors simultaneously might overburden participants. Thus, the aim of the study was to (a) investigate the relationship between these two health behaviors, (b) assess the perceived intergoal conflict and coherence, and (c) test the effects of stage-matched and mismatched interventions on perceived intergoal conflict and coherence.
Methods: Based on the Health Action Process Approach (HAPA; Schwarzer, 2008), which describes behavior change as a process with qualitatively different stages, an internet-based health prevention program was tested. The quasi-experimental study with two different interventions included N = 1260 and a longitudinal subsample with n = 300 participants.
Results: Results showed that both health behaviors are correlated, and that participants perceived more intergoal facilitation than conflicts. Perceived conflict varied between participants in the different HAPA stages. Stagematched interventions successfully reduced intergoal conflict.
Conclusion: Health promotion programs that simultaneously target physical activity and dietary behavior seem not to overburden participants. On the contrary, participants report high levels of intergoal coherence between the two goals. Nonetheless, intergoal conflicts do play a role in the early stages of behavior change and intention formation. Health promotion programs should take these results into consideration when more than one health behavior is to be targeted.