Overview
Population aging is a global public health challenge. This cross-sectional study investigates sarcopenia and sarcopenic obesity (SO) in community-dwelling adults aged 60 and older in Shanghai, aiming to estimate prevalence, explore associations with body composition and biochemical markers, and identify factors linked to sarcopenia. Using the 2019 Asian Working Group for Sarcopenia (AWGS) criteria and WHO guidelines for obesity, the research provides urban, contemporary insights for clinical practice and public health planning.
Methods at a glance
From January to December 2021, 700 older adults attending a Shanghai health examination center were assessed. Participants provided demographic data, underwent anthropometric measurements, laboratory tests, and body composition analysis via bioelectrical impedance (InBody 270). Sarcopenia was diagnosed if participants met AWGS criteria based on appendicular skeletal muscle mass index (ASMI), grip strength, and/or 6‑m walking speed. Obesity was defined by body fat percentage (PBF) per WHO thresholds. Based on sarcopenia and obesity status, participants were categorized into four phenotypes: sarcopenic obesity (SO), sarcopenia without obesity, obesity without sarcopenia, and non-sarcopenia/non-obesity. Statistical analyses included univariate and multivariate logistic regression to identify independent factors associated with sarcopenia.
Key findings: prevalence and phenotypes
The study found a sarcopenia prevalence of 13.6% and a SO prevalence of 6.9% among participants. SO individuals were the oldest on average (mean age around 70 years) and showed the lowest ASMI with marked sex differences. These results support the notion that the muscle‑fat balance worsens with age and that visceral adiposity contributes to sarcopenia risk.
Sex differences and body composition
Sex-specific analyses revealed notable patterns. Men with sarcopenia tended to have higher absolute skeletal muscle mass and ASMI than women but still exhibited greater age-related decline. Women, by contrast, had higher body fat percentages, hinting at greater fat infiltration in muscle despite lower muscle mass. Such sex differences highlight the need for gender-tailored screening and interventions that address both muscle preservation and adiposity management in older adults.
Independent predictors of sarcopenia
Multivariate analysis identified several independent predictors of sarcopenia:
– Age, especially ≥ 79 years, markedly increasing risk (OR ~11.3).
– Visceral fat area (VFA): each additional cm² raised sarcopenia odds (OR ~1.14).
– Low ASMI: a strong predictor with very high odds (OR ~87.2).
– Sex: female sex emerged as a protective factor in this cohort (OR ~0.07).
These findings emphasize that both muscle quantity and visceral adiposity are central to sarcopenia risk, with aging amplifying these effects. Higher VFA likely reflects pro-inflammatory states that contribute to muscle catabolism, while low ASMI signals loss of lean mass critical to function.
Biochemical and lifestyle considerations
The analysis touched on biochemical indicators such as albumin and lipid profiles, suggesting links between nutritional status, metabolic health, and sarcopenia. Although some lifestyle factors appeared associated with sarcopenia in univariate analyses, their significance diminished after adjustment, underscoring the primacy of aging, muscle mass, and visceral adiposity. The urban, higher‑socioeconomic setting of Shanghai residents may influence dietary quality and access to resources that support muscle health, yet age‑related processes remain dominant determinants.
Implications for practice and policy
This study provides the first Shanghai‑level estimates of sarcopenia and SO in adults aged 60 and above, with implications for screening and intervention. Clinicians should prioritize early sarcopenia screening, particularly among older men and individuals with increasing visceral fat or declining ASMI. Interventions combining resistance exercise with protein‑rich nutrition and strategies to reduce visceral adiposity may help preserve muscle mass and function, potentially reducing disability, falls, and healthcare costs in urban aging populations.
Limitations and future directions
Limitations include the cross‑sectional design, convenience sampling from a single center, and variability in sarcopenia/SO definitions. The relatively small SO subgroup limited multivariate modeling for that phenotype. Longitudinal studies with diverse urban populations are needed to clarify causality, track progression, and assess intervention effectiveness.
Conclusion
In Shanghai’s aging population, sarcopenia and SO are meaningful public health concerns linked to age, visceral fat, and lean mass decline. Early, sex‑sensitive screening and integrated lifestyle interventions are warranted to protect muscle health and mitigate the broader health burden of aging in China’s bustling metropolis.
