Traditional Chinese medicine constitution-related body-composition phenotypes and 1-year metabolic changes: a repeated health-examination study

Background Traditional Chinese medicine (TCM) constitution is widely used for health stratification, yet its correspondence with objectively measured body composition and the metabolic relevance of short-term body-composition changes remain unclear. Methods Repeated cross-sectional analyses included 1,180, 2,530, and 6,791 participant-year observations in 2023, 2024, and 2025, respectively. Associations between TCM constitution and appendicular skeletal muscle mass index (ASMI), phase angle, body fat percentage (PBF), and visceral fat area (VFA) were estimated using multivariable linear regression, with Balanced constitution as the reference. The 2024–2025 repeated-examination cohort included 997 participants; 735 without metabolic abnormality clustering at baseline formed the incident cohort. Baseline-adjusted linear models examined associations of 1-year body-composition changes with follow-up metabolic markers, and modified Poisson regression estimated risk ratios (RRs) for incident clustering. Additional analyses accounted for concurrent body mass index (BMI) change and examined temporal consistency, dose–response patterns, and robustness. Results In 2025, Yang-deficiency constitution was associated with lower ASMI (−0.052 SD) and phase angle (−0.096 SD) and higher PBF (0.073 SD) and VFA (0.053 SD) after adjustment for age, sex, and BMI. Phlegm-dampness constitution was associated with lower phase angle (−0.117 SD) and higher PBF (0.058 SD) and VFA (0.054 SD). These phenotype patterns were directionally consistent across calendar years. During follow-up, 140 of 735 participants (19.0%) developed metabolic abnormality clustering. Per 1-SD increases in PBF and VFA change were associated with RRs of 1.18 (95% CI 1.03–1.37) and 1.22 (95% CI 1.07–1.40), respectively. After additional adjustment for concurrent BMI change, the corresponding RRs were 1.04 (95% CI 0.85–1.26) and 1.11 (95% CI 0.92–1.34), indicating that short-term adiposity changes largely paralleled changes in overall body weight. Conclusion TCM constitution categories corresponded to modest, multidimensional body-composition phenotypes that were consistent across repeated calendar-year samples. Increases in total and visceral adiposity were associated with adverse metabolic changes over the same 1-year interval and with incident metabolic-abnormality clustering at follow-up, largely in parallel with BMI change. These findings provide an objective basis for characterizing constitution-related phenotypes and monitoring metabolic remodeling in routine health examinations.