Methylation of PGC1A (peroxisome proliferator-activated receptor γ coactivator 1 alpha), a transcription factor critical in energy expenditure, and of IGF-2 (insulin-like growth factor 2), was disrupted in high fat diet (HFD), gestational diabetes, and obesity, with caloric restriction restoring the methylation state [31]. This evidence concerns the gene PPARGC1A and obesity due to melanocortin 4 receptor deficiency.