In contrast, as presented in Fig. 4B, SIRT1 protein content increased with resveratrol in only myotubes from lean subjects (1.2 ± 0.04 fold increase over the nonresveratrol condition, P < 0.05) and changed enough to be significantly higher in lean participants than participants with severe obesity (P < 0.05). This evidence concerns the gene SIRT1 and obesity due to melanocortin 4 receptor deficiency.