OPRM1 and obesity due to melanocortin 4 receptor deficiency: Study examined transcriptional regulation and epigenetic modifications of Cnr1 and Oprm1 in hypothalamus of diet‐induced obesity rats (5 and 21 weeks on high‐fat diet) and humans with obesity. Gene expression and DNA methylation at gene promoters were analyzed to identify time‐dependent changes and potential biomarkers for obesity development.