FOXO3 and Atrophy: Additional studies have shown that CR regulates the transcription factor Forkhead box O3 (FOXO3), which is associated with human longevity [77], and recent studies have shown that muscle atrophy is associated with the expression of the transcription factor FOXO3 and other downstream target skeletal muscle atrophy-related proteins, namely, Atrogin 1 and MuRF1 [78].