We study the molecular mechanisms that regulate muscle cell size. A reduction in muscle size during aging or disease results from an excessive proteolysis by the proteasome and autophagy, leading to frailty, disability, and death. We strive to understand the catabolic pathways and cellular processes that precede and promote this debilitating loss of muscle mass in order to develop rational therapies to combat wasting. Our research encompasses different fields from physiology and metabolism, through protein biochemistry and cell biology. Our goal is to advance foundational understanding of diverse types of wasting, highlighting how cells retain and adapt their size to a changing physiological environment.