Abstract
Introduction: Circadian misalignment has been proposed as a potential determinant of cardiometabolic risk. Chronotype, as an expression of individual circadian organization, has been associated with unfavorable metabolic profiles; however, the role of total and central adiposity as potential mediating mechanisms in this relationship remains incompletely understood. Objective: This study aimed to analyze the association between chronotype and cardiometabolic risk in adults and to evaluate the potential mediating role of body fat percentage (BF%) and waist-to-height ratio (WHtR). Methods: An observational study was conducted in 1462 adults from the general population. Chronotype was assessed using the Morningness-Eveningness Questionnaire (MEQ), and cardiometabolic risk was evaluated using a continuous cardiometabolic risk score (CMRS) derived from waist circumference (WC), systolic blood pressure (SBP), triglycerides (TG), fasting blood glucose (FBG), and total cholesterol (TC). Multiple linear regression models adjusted for covariates were used to examine the association between chronotype and CMRS, and hierarchical regression was performed to estimate the incremental contribution of adiposity indicators. Mediation analysis was conducted using the PROCESS macro (Model 4) with 95% bootstrap confidence intervals. Results: Chronotype was independently associated with CMRS after adjustment for covariates (β = 0.055; p = 0.030), although the effect size and explained variance were small. In hierarchical regression analysis, the inclusion of chronotype explained a small but significant increase in CMRS variance (ΔR(2) = 0.003; p = 0.030). The addition of adiposity indicators significantly increased the explained variance (ΔR(2) = 0.014; p < 0.001), with WHtR emerging as the most relevant predictor in the final model. Bootstrap mediation analysis did not reveal significant indirect effects of BF% or WHtR on the relationship between chronotype and CMRS. In sensitivity analyses excluding waist circumference from the CMRS, the association between chronotype and cardiometabolic risk was no longer significant (β = -0.001; p = 0.974). Conclusions: Chronotype showed a modest association with cardiometabolic risk in the primary analysis. However, sensitivity analyses indicated that this association may partly depend on the inclusion of waist circumference within the composite cardiometabolic risk score. These findings highlight the central role of abdominal adiposity in cardiometabolic health and suggest that the relationship between chronotype and cardiometabolic risk should be interpreted with caution.