Associations between sarcopenic, obesity, and sarcopenic obesity and metabolic syndrome in adults aged 45 Years or older: A prospective cohort study from the China health and retirement longitudinal study.

Although previous studies have reported associations between sarcopenic obesity (SO) and metabolic syndrome (MetS), the findings remain inconsistent. This study aimed to investigate the associations between sarcopenia, obesity, and MetS, and to determine whether sarcopenic obesity synergistically increases the risk of MetS.

The data were extracted from the China Health and Retirement Longitudinal Study (CHARLS) in 2011 and 2015. Participants were categorized into five groups: non-sarcopenia non-obesity, non-sarcopenia obesity, non-obesity sarcopenia, possible SO, and SO.

MetS was defined using the diagnostic criteria recommended by the National Cholesterol Education Program Adult Treatment Panel III. Logistic regression models were employed for both cross-sectional and longitudinal analysis.

In 2011, a total of 9322 participants were included in the cross-sectional analysis, with 3674 individuals followed up in 2015. In the cross-sectional study, non-sarcopenia obesity (OR = 9.20, CI: 8.06 to 10.50), possible SO (OR = 2.04, CI: 1.94 to 2.15), and SO (OR = 1.61, CI: 1.47 to 1.77) were associated with a higher prevalence of MetS.

In contrast, non-obesity sarcopenia (OR = 0.85, CI: 0.74 to 0.98) was associated with a lower prevalence. In the longitudinal analysis, non-sarcopenia obesity (OR = 2.87, CI: 2.34 to 3.52) and possible SO (OR = 1.41, CI: 1.30 to 1.53) were associated with an increased incidence of MetS, while non-obesity sarcopenia (OR = 0.75, CI: 0.62 to 0.91) was associated with a reduced incidence.

Notably, SO (OR = 1.00, CI: 0.80 to 1.25) was not associated with the incidence of MetS. Possible SO, defined by low muscle mass, was not associated with subsequent new-onset MetS.

This study highlights that the obesity component, rather than the muscle mass component, is the primary driver of MetS risk in middle-aged and older adults in China.