The relationship between habit and identity in health behaviors: A systematic review and three-level meta-analysis.

Habit and identity are two key determinants of health behavior maintenance. However, the relationship between habit and identity remains inconsistently interpreted, with empirical findings showing varying correlations. This meta-analytic review aimed to synthesize the effect sizes of the relationship between habit and identity in health behaviors and to further explore the moderators that influence this relationship. A search of eight databases (PubMed, Web of Science, Scopus, MEDLINE, CINAHL, PsycArticles, PsycINFO, and SPORTDiscus) was conducted up to October 9, 2024. Nineteen articles related to physical activity, healthy eating, and drinking were identified based on eligibility criteria, including 32 effect sizes and a total of 13,340 participants. The results indicated a significant positive correlation between habit and identity with a large effect size (r = 0.55, 95% CI [0.49, 0.74]). A multiple moderator analysis revealed that effect sizes were larger when identity was measured using explicit tests. The moderating effects of different types of health behaviors and geographic location were not sufficiently supported. Limited predictive studies imply that the relationship between habit and identity might not be unidirectional. Finally, this review calls for the integration of knowledge of habit and identity to facilitate the practice of health behavior change.