POMC and obesity due to melanocortin 4 receptor deficiency: Moreover, after three months of obesity induction, the mean methylation levels of the CpG sites in the promoter regions of the leptin and POMC genes did not show any differences between the n-3 PUFA-deficient diet (83% and 65.2%) and n-3 PUFA-containing diet groups (81% and 65.1%).