Based on this evidence, and the central role of PGC-1α gene expression in regulating mitochondrial biogenesis (Ventura-Clapier et al., 2008; Kang and Li Ji, 2012; Halling and Pilegaard, 2020), we hypothesized that muscle mitochondrial protein synthesis increases during the collective time period that includes aerobic exercise and post-exercise recovery in humans without obesity, but not in humans with obesity. This evidence concerns the gene PPARGC1A and obesity due to melanocortin 4 receptor deficiency.