Sarcopenic Obesity Revisited: Insights From the Mr and Ms Os Cohort

Following the concept of a metabolic load-capacity model, we propose the use of appendicular skeletal muscle mass (ASM) to total body fat (TBF) ratio in predicting 4-year physical limitations, physical performance measures, 6-year incident diabetes and cardiovascular diseases, and 12-year mortality.

Cross-sectional and prospective cohort study.

4000 men and women aged 65 years and older living in the community.

At baseline, information regarding physical limitation was obtained. Measurements included height, weight, body composition using dual-energy x-ray absorptiometry, grip strength, and walking speed. Total ASM was calculated as the sum of appendicular lean mass minus bone mineral content of both arms and legs. Gait speed was measured using the best time in seconds to complete a walk along a straight line 6 m long. The mean ASM/TBF ratio was estimated for the combination categories of (1) no sarcopenia and TBF less than top quartile (by sex), (2) sarcopenia and TBF less than top quartile, and (3) sarcopenia and TBF larger than top quartile. Association of quintiles of ASM/TBF with mortality was analyzed using Cox regression; logistic regressions were applied to examine other outcomes. Cutoff values of ASM/TBF were identified by Classification and Regression Tree (CART) analysis for different outcomes.

Compared with those with the highest quintile of ASM/TBF, men in the lowest quintile had a 79% increase in risk of physical limitations, 66% increase in risk of slow walking speed, and 80% increase in incident cardiovascular diseases. In women, increased risk was only observed for physical limitation and slow walking speed. CART analysis identified different cutoff values for different outcomes and also between men and women.

ASM/TBF may be used in geriatric screening to detect sarcopenic obesity, to guide implementation of weight control, as well as in muscle-strengthening programs.