Sarcopenic Obesity: A Critical Appraisal of the Current Evidence

Sarcopenic obesity (SO) is assuming a prominent role as a risk factor because of the double metabolic burden derived from low muscle mass (sarcopenia) and excess adiposity (obesity). The increase in obesity prevalence rates in older subjects is of concern given the associated disease risks and more limited therapeutic options available in this age group. This review has two main objectives. The primary objective is to collate results from studies investigating the effects of SO on physical and cardio-metabolic functions. The secondary objective is to evaluate published studies for consistency in methodology, diagnostic criteria, exposure and outcome selection. Large between-study heterogeneity was observed in the application of diagnostic criteria and choice of body composition components for the assessment of SO, which contributes to the inconsistent associations of SO with cardio-metabolic outcomes. We propose a metabolic load:capacity model of SO given by the ratio between fat mass and fat free mass, and discuss how this could be operationalised. The concept of regional fat distribution could be incorporated into the model and tested in future studies to advance our understanding of SO as a predictor of risk for cardio-metabolic diseases and physical disability.