The secretion of both IGF-I and IGF-II, peptides that are structurally related to insulin, is linked to nutrient intake. These growth factors and their binding proteins appear to be major links between nutrient intake and cellular anabolic responses. Understanding the mechanisms by which nutrients control IGF synthesis and regulate transport to target tissues should permit the formulation of strategies for treatment of catabolic disorders. Understanding the alterations of such processes in catabolic states should enable development of better methods for nutritional repletion and wiser uses of anabolic agents in the treatment of these conditions.