Obesity Measures and Definitions of Sarcopenic Obesity in Singaporean Adults - the Yishun Study.

Background: The prevalence of sarcopenic obesity (SO) and its effects on functional disability are of particular concern. Due to the lack of a uniform obesity definition, there is marked variability in reported SO prevalence and inconsistent data on observed adverse health outcomes.

Objectives: We compare SO prevalence and the associations of SO with physical function using sarcopenia according to current Asian Working Group for Sarcopenia (AWGS) guidelines and with different obesity measures. We recommend that the most optimal SO diagnostic formulation would be one that is most significantly associated with reduced physical function.

Design: 535 healthy, community-dwelling Singaporeans were recruited (21-90 years old, 57.9% women). We assessed anthropometry, body composition, and questionnaire-based physical and cognitive factors, and estimated SO prevalence with obesity defined according to waist circumference (WC), percentage body fat (PBF), fat mass index (FMI) and fat mass/fat-free mass ratio (FM/FFM). Muscle function was compared among phenotypes and obesity definitions using ANOVA. Differences across obesity measures were further ascertained using multiple linear regressions to determine their associations with the Short Physical Performance Battery (SPPB).

Results: Overall prevalence of SO was 7.6% (WC-based), 5.1% (PBF-based), 2.7% (FMI-based), and 1.5% (FM/FFM-based). The SO phenotype consistently performed poorer than the obese group (p<0.05) except for FM/FFM-based measure, and performed poorer than the sarcopenic group in SPPB (p<0.05) only in the PBF and FMI-based measures. SO was significantly associated with SPPB in the PBF and FMI models (p<0.05). Total variance explained by the different regression models was highest for the FMI definition.

Conclusions: Our findings suggest FMI as the most preferred measure for obesity and support its use as a diagnostic criteria for sarcopenic obesity.