Not always protective: health literacy, school connectedness and adolescent healthy eating behaviors-the moderating role of physical activity participation.

Purpose: To explore the effects of Health literacy on adolescent healthy eating behaviors, a moderated-mediation model was constructed in this study to examine the mediating effect of School connectedness and the moderating effect of Physical activity participation. Methods: Stratified cluster sampling was adopted. Questionnaires were administered to 3, 009 middle-school students recruited from 12 middle schools across 6 provinces nationwide, using the Health literacy scale, Eating behaviors scale, School connectedness scale, and Physical activity participation scale. Data analyses were performed using SPSS 26.0 and PROCESS Model 15. Results: (1) Health literacy was significantly and positively associated with adolescent healthy eating behaviors. (2) A statistically significant indirect effect through School connectedness was identified; however, its direction was opposite to the hypothesized positive mediation, indicating a suppression pattern. (3) Physical activity participation significantly moderated the direct association between Health literacy and healthy eating behaviors, with this positive association progressively weakening as Physical activity participation increased. (4) Physical activity participation also moderated the second stage of the indirect pathway (School connectedness → healthy eating behaviors). The suppression pattern was stronger at low levels of Physical activity participation but was attenuated and statistically reversed at high levels, where the conditional indirect effect became weakly positive. Conclusion: Adolescent healthy eating behaviors are shaped by the interactive effects of individual cognition, school environments, and adolescents' motivational tendency for sports-participation within institutional school physical-activity contexts. School connectedness may function as a counteracting factor in the association between Health literacy and healthy Eating behaviors; however, this counteracting effect is contingent upon Physical activity participation, disappearing and shifting toward a weak positive effect at high levels of Physical activity participation. These findings highlight the importance of jointly considering Health literacy, School connectedness, and Physical activity participation in school-based health promotion. However, given the cross-sectional design and the small positive indirect effect observed at high levels of Physical activity participation, further longitudinal and intervention studies are needed before specific stratified intervention strategies are recommended.