Objective:

To identify body composition phenotypes and compare physical function across phenotypes among community-dwelling older adults, with a secondary exploratory analysis of limb muscle mass asymmetry.

Approach:

• Study Design: Cross-sectional study involving 600 community-dwelling adults aged 60–79 years in Bengbu, Anhui, China.
• Body Composition Assessment: Body composition was assessed using bioelectrical impedance analysis, focusing on body fat percentage, trunk fat mass, and lower-limb muscle mass.
• Phenotype Identification: Latent profile analysis was used to identify body composition phenotypes.
• Physical Function Assessment: Physical function was evaluated using various tests including grip strength and balance assessments.
• Statistical Analysis: ANCOVA, linear regression, logistic regression, and subgroup analyses were performed, with FDR correction applied.

Key Findings:

• Three body composition phenotypes identified: low-adiposity phenotype (C1, 27%), balanced phenotype (C2, 55%), and high-adiposity–high-muscle phenotype (C3, 18%).
• Significant differences in grip strength (P = 0.003), one-leg stance with eyes closed (P = 0.002), and 30-s chair stand performance (P = 0.003) across phenotypes after adjusting for age and sex.
• No significant associations between limb muscle mass asymmetry and functional performance outcomes after FDR correction.

Interpretation:

Body composition phenotypes may provide insights into functional heterogeneity in older adults.

Limitations:

• Study is cross-sectional, limiting causal inferences.
• Sample limited to a specific geographic area, which may affect generalizability.
• Potential confounding factors not fully controlled.

Conclusion:

The study highlights the heterogeneity of body composition phenotypes in older adults and their association with physical function.