Recently, Peres et al. [45] showed that obesity causes the deficiency of peroxisome proliferator-activated receptor-γ (PPARγ) coactivator 1α (PGC-1α), a transcriptional coactivator and master regulator of mitochondrial biogenesis in the pancreas. This evidence concerns the gene PPARGC1A and obesity due to melanocortin 4 receptor deficiency.