Health Consequences of Sarcopenic Obesity: A Narrative Review

Abstract

Sarcopenia is defined as the age-related loss of muscle mass and strength or physical performance. Increased amounts of adipose tissue often accompany sarcopenia, a condition referred to as sarcopenic obesity. The prevalence of sarcopenic obesity among adults is rapidly increasing worldwide. However, the lack of a universal definition of sarcopenia limits comparisons between studies. Sarcopenia and obesity have similar pathophysiologic factors, including lifestyle behaviors, hormones, and immunological factors, all of which may synergistically affect the risk of developing a series of adverse health issues. Increasing evidence has shown that sarcopenic obesity is associated with accelerated functional decline and increased risks of cardiometabolic diseases and mortality. Therefore, the identification of sarcopenic obesity may be critical for clinicians in aging societies. In this review, we discuss the effect of sarcopenic obesity on multiple health outcomes and its role as a predictor of these outcomes based on the components of sarcopenia, including muscle mass, muscle strength, and physical performance.

Keywords: aging; lean body mass; morbidity; muscle strength; obesity; sarcopenia.

Figure 1

Schematic biological pathways that lead to sarcopenic obesity with age. Aging accompanies with reduced metabolic rate, decreased physical activity, and sex-specific hormonal changes. These changes contribute to aging-related decrease in muscle mass and strength as well as increase in body fat and unfavorable changes in body fat composition, such as a loss of subcutaneous fat, an accumulation of visceral fat, and ectopic fat deposition. Obesity in aged individuals stimulates ectopic fat accumulation in skeletal muscles, which leads to marked impairment of mitochondria fatty acid oxidation, increased oxidative stress, and insulin resistance, resulting in decline in muscle mass and strength. Moreover, obesity-associated adipose tissue inflammation can affect skeletal muscle mass and function by the increased production of pro-inflammatory cytokines and adipokine leptin, and decreased action of adiponectin and IGF-1. Aging-associated sarcopenic obesity is correlated to multiple adverse cardiometabolic effects and contributes to poor health outcomes.