CLOCK and obesity due to melanocortin 4 receptor deficiency: Interestingly, the gene we found to have the greatest magnitude of change in response to all three exercise treatments was the reduction in gene expression of the core clock component, NR1D1 (Rev-Erbα), which was recently reported to play a critical role in adipose tissue abnormalities common in obesity (e.g., fibrotic ECM and macrophage infiltration) (54).