Introduction
As populations age globally, sarcopenia—an age-related loss of muscle mass and function—poses increasing health and economic challenges. When obesity coexists with sarcopenia, the adverse outcomes amplify, a condition termed sarcopenic obesity (SO). This cross-sectional study investigates the prevalence of sarcopenia and SO among older adults in Shanghai and explores their associations with body composition and biochemical markers, aiming to identify independent risk factors for sarcopenia and provide actionable insights for clinical practice and public health.
Methods
The study recruited 700 community-dwelling adults aged 60 and older who attended a Shanghai health examination center in 2021. Participants underwent comprehensive assessments including anthropometrics, laboratory tests, and body composition analysis via bioelectrical impedance (InBody 270). Sarcopenia diagnosis followed the 2019 AWGS criteria, requiring the presence of low appendicular skeletal muscle mass index (ASMI), diminished grip strength, and/or slow gait speed. Obesity was defined by percent body fat (PBF) per WHO cutoffs. Participants were categorized into four groups: sarcopenia with obesity (SO), sarcopenia without obesity, obesity without sarcopenia, and non-sarcopenia/non-obesity. Logistic regression identified independent risk factors for sarcopenia and SO where feasible, with careful handling of missing data.
Key findings on prevalence and phenotypes
The overall prevalence of sarcopenia was 13.6%, while SO stood at 6.9%. The SO group tended to be the oldest and showed the lowest ASMI alongside higher visceral fat area (VFA). Visceral adiposity emerged as an independent predictor of sarcopenia after adjustment, underscoring the muscle-fat imbalance that accompanies aging. These findings align with the view that visceral fat contributes to muscle catabolism through inflammatory pathways, heightening the risk of functional decline.
Sex differences and clinical implications
Significant sex differences were observed. Males accounted for a larger share of sarcopenia without obesity and the SO group, suggesting sex-specific patterns in muscle and fat distribution. Compared with females, men had higher absolute muscle mass and ASMI, yet sarcopenia still rose with age in both sexes. The data emphasize the need for sex-specific screening and prevention strategies, focusing on preserving muscle mass in older men while addressing fat-muscle balance in older women.
Independent risk factors for sarcopenia
Multivariate analysis highlighted several strong predictors of sarcopenia: age ≥ 79, lower ASMI, male sex, and increased VFA. In particular, ASMI was a powerful indicator, reflecting lean mass deficits, while visceral fat’s metabolic activity may fuel inflammatory processes that drive muscle breakdown. These results support integrated prevention approaches targeting both muscle preservation and fat reduction in aging populations.
Limitations and future directions
As a cross-sectional study based in a single center, causal inferences are limited and generalizability may be affected by participant selection. The study did not include dietary intake or physical activity data, which are relevant to sarcopenia risk. Future longitudinal studies with diverse urban and rural populations are needed to validate these findings, refine diagnostic criteria, and evaluate interventions that combine resistance training with nutritional optimization to mitigate SO and sarcopenia.
Conclusions
This Shanghai-based study provides updated estimates of sarcopenia and SO in older adults and identifies key body composition and biochemical correlates. The results call for early, gender-sensitive screening and targeted interventions to preserve muscle health, reduce visceral adiposity, and ultimately improve quality of life and healthcare outcomes for China’s aging population.
