Muscle-adipose aging reflects population-specific patterns of inflammatory and lipolytic reprogramming, with metabolic efficiency—rather than absolute tissue quantity—emerging as a key determinant of healthy aging.
Key Findings
Results
Muscle-adipose aging patterns differed substantially across UK, US, and Taiwanese populations, with Taiwanese men showing steeper cross-sectional differences in appendicular lean mass decline while maintaining higher muscle-to-fat ratios than other cohorts.
Data were drawn from UK Biobank (n = 35,436), US NHANES (n = 9,157), and Taiwan NAHSIT (n = 4,959)
Taiwanese men had lower absolute appendicular lean mass compared to Western cohorts
Despite lower absolute muscle mass, Taiwanese men maintained higher muscle-to-fat ratios than counterparts in UK and US cohorts
Age-specific patterns were described with particular attention to masking effects of BMI adjustment and late-life metabolic selection
Results
Inflammaging patterns were consistent across all three cohorts, with CRP increasing by up to 90% and IGF-1 declining by 20.3%–23.8% from ages 45 to 79.
Inflammaging was assessed using C-reactive protein (CRP) and insulin-like growth factor-1 (IGF-1) decline profiles
CRP increased by up to 90% across the age range of 45 to 79 years
IGF-1 declined by 20.3%–23.8% across the same age range
These patterns were described as consistent with a potential link between chronic inflammation and anabolic resistance
The consistency of these patterns was observed across ethnically diverse populations from three separate national cohorts
Results
BMI-adjusted muscle mass showed greater deterioration with age compared with height-adjusted measures, suggesting conventional assessments may mask sarcopenic progression.
Two adjustment approaches were compared: BMI-adjusted and height-adjusted muscle mass measures
BMI adjustment revealed greater age-related muscle mass deterioration than height adjustment
The authors concluded that conventional BMI-based assessments may mask the true extent of sarcopenic progression
This finding was described as having implications for risk stratification in aging populations
Results
Adiposity trajectories peaked earlier in Western populations (ages 55–59 years) than in Taiwanese adults (ages 60–64 years), followed by late-life declines of 10.3%–23.5% suggestive of differential lipolytic activation.
Peak adiposity occurred at ages 55–59 years in UK and US cohorts
Peak adiposity occurred at ages 60–64 years in the Taiwanese cohort
Late-life adiposity declines ranged from 10.3% to 23.5% across the populations studied
These declines were described as indicative of differential lipolytic activation across populations
The timing difference suggests population-specific differences in fat metabolism trajectories with aging
Results
Ketone body concentrations increased with age in the UK cohort, suggesting higher fat oxidation in older age groups.
Lipolytic activity was evaluated using circulating ketone bodies: β-hydroxybutyrate, acetoacetate, and acetone
Ketone body data were available only from the UK Biobank cohort (n = 35,436)
Concentrations of all three ketone body markers increased with age
The authors interpreted this as evidence of higher fat oxidation in older age groups
This finding was used to support the hypothesis of age-related lipolytic reprogramming
Results
Among adults aged 80 years or older, reversals in the muscle-to-fat ratio were observed across all populations, suggesting metabolic selection effects in the oldest age groups.
The reversal in muscle-to-fat ratio trajectories was observed in the 80+ age group across all three cohorts (UK, US, and Taiwan)
This pattern was interpreted as indicative of metabolic selection effects, meaning that only metabolically advantaged individuals survive to older ages
The authors noted this as a late-life phenomenon distinct from the patterns observed in middle and early older age
This finding was described as consistent with survivor bias in cross-sectional aging studies
Conclusions
The authors propose that establishing ethnically tailored reference standards may improve precision of aging-related risk stratification and interventions across diverse populations.
Current findings revealed that population-specific differences in muscle mass, adiposity, and metabolic trajectories are substantial
The study covered populations from three distinct ethnic and geographic backgrounds: UK (predominantly European), US (multi-ethnic), and Taiwan (East Asian)
The authors argued that metabolic efficiency—rather than absolute tissue quantity—is a key determinant of healthy aging
Ethnically tailored standards were proposed as a way to improve clinical and public health interventions related to sarcopenia and inflammaging
What This Means
This research suggests that how muscles and body fat change with aging differs meaningfully between populations from the United Kingdom, United States, and Taiwan. Even though Taiwanese men had less total muscle mass than their Western counterparts, they maintained a healthier balance between muscle and fat. Meanwhile, Western populations tended to accumulate peak body fat earlier in life (in their late 50s) compared to Taiwanese adults (early 60s), with all groups showing notable fat loss in very old age. These differences point to population-specific patterns in how the body manages fat metabolism as it ages.
The study also found that markers of chronic low-grade inflammation (a process sometimes called 'inflammaging') rose consistently across all three populations with age—CRP levels increased by up to 90% and a key muscle-building hormone (IGF-1) fell by about 20–24% between ages 45 and 79. Additionally, older adults in the UK cohort showed higher levels of ketone bodies in their blood, which suggests their bodies were burning more fat for energy as they aged. The researchers also found that the way muscle mass is measured matters: adjusting for BMI rather than height made age-related muscle loss look more severe, meaning some standard clinical tools may actually be underestimating how much muscle people lose as they get older.
This research suggests that a 'one size fits all' approach to assessing muscle and fat health in aging populations may be inadequate. Because aging trajectories differ across ethnic groups, health standards and risk thresholds developed in one population may not translate well to others. The findings point to a need for ethnically tailored reference standards to better identify who is at risk for muscle loss and related health problems—ultimately helping clinicians and public health professionals design more targeted prevention and treatment strategies for aging populations worldwide.
Hsiao F, Wu J, Chen I, Lin Y, Meng L, Chen L. (2026). Muscle-Adipose Aging Dynamics and Inflammaging Patterns Across Ethnically Diverse Populations: Exploring Potential Roles of Lipolysis.. Journal of cachexia, sarcopenia and muscle. https://doi.org/10.1002/jcsm.70316