MSTN and protein-energy malnutrition: Mechanisms underlying sarcopenia in patients with liver disease have been reported to involve protein-energy malnutrition, which is characteristic of patients with cirrhosis, signaling involved in protein synthesis and degradation, myokines such as IGF-1, myostatin, and decorin, the ubiquitin-proteasome pathway, sex hormones such as testosterone, dysbiosis, insulin resistance, etc., in addition to aging [29,30,31,32] (Figure 1).