A study by Pucci et al. revealed a significant and selective increase in CNR1 gene expression in high-fat-diet rats at the beginning of obesity development and after 21 weeks of high dietary exposure, with a simultaneous selective and significant decrease in DNA methylation at specific CpG sites in both gene promoters in overweight rats [148]. The gene discussed is CNR1; the disease is obesity due to melanocortin 4 receptor deficiency.