Unveiling the relation among mental health, dietary quality, health literacy, loneliness, physical activities, and BMI in young Chinese

This study aims to examine the complex interrelationships among dietary quality, health literacy, loneliness, physical activity, mental health, and BMI (Body Mass Index) among young Chinese individuals, with particular attention to the mediating role of mental health in the pathways linking health behaviors and BMI. A cross-sectional survey was conducted with a diverse sample of Chinese university students ( N = 1568) using validated instruments to measure dietary quality, health literacy, loneliness, physical activity, mental health, and BMI. Structural equation modeling (SEM) was employed to test both direct and indirect relationships among the variables. Findings revealed that higher levels of dietary quality, health literacy, and physical activity were significantly associated with better mental health, while loneliness showed a strong negative effect. Mental health was, in turn, negatively associated with BMI. Furthermore, mental health significantly mediated the effects of dietary quality, health literacy, and physical activity on BMI. These results underscore the central role of psychological well-being in converting health knowledge and behaviors into tangible physical outcomes. The study highlights the need for integrated health promotion strategies that address not only physical behaviors and informational competencies but also the emotional and social dimensions of health. Strengthening mental health support and health literacy among youth may enhance the effectiveness of dietary and physical activity interventions, contributing to the broader goals of the Healthy China 2030 initiative.