An Overview of Sarcopenic Obesity

Sarcopenic obesity (SO) refers to the copresence of sarcopenia and obesity. In this condition, a disproportion exists between the amount of lean mass relative to fat mass. Research on SO is important because the presence of both sarcopenia and obesity may have important health consequences. However, SO research has been hampered by the disparate number of definitions of SO. Various definitions of sarcopenia include ratios of appendicular mass to height2 or body weight, measures of muscle strength, or physical function. More recent definitions incorporate all 3. Obesity is usually defined by high body mass index, but some studies have relied on percent body fat or visceral fat. Depending on the definition, the prevalence of SO ranges from 0% to 41% in older populations. The loss of lean mass and increase in fat mass with advancing age may share common etiologic pathways. Declines in physical activity can lead to poor muscle strength, lower muscle mass, and increased fat infiltration; all of which could lead to increases in fat mass. The increases in fat mass and accompanying increases in adipokines and inflammation may further adversely affect muscle quality. SO has been related to an increased risk of mobility disability, above and beyond sarcopenia, or obesity alone. Additional research is needed to further our understanding of the pathophysiology of SO and its consequences. Interventions aimed at reducing SO may improve physical function as well as reduce disability and death.