This review describes our studies on compensatory growth, specifically the growth that occurs after dietary lysine deficiency is changed to sufficiency. We found that dietary lysine sufficiency induced compensatory growth in pigs after dietary lysine deficiency. We also showed that compensatory growth of pigs induced by dietary lysine sufficiency was partly attributed to greater N retention. In a rat model, both suppression of proteolysis and increased protein synthesis in skeletal muscle contributed to their compensatory growth with lysine sufficiency. Finally, our in vitro studies with cultured skeletal muscle cells revealed that the compensatory growth in these cells was induced by increased lysine levels in combination with the modulation of insulin-like growth factor-I and glucocorticoid levels. This suggested that compensatory growth in pigs and rats with lysine sufficiency was due to both increased serum lysine levels and changes in the levels of hormones involved in protein synthesis and degradation.