LEPR and obesity due to melanocortin 4 receptor deficiency: While the SHR/NDmcr-cp (SHR) rat model has been known to develop metabolic disorders due to its genetic deficiency in leptin receptor [11], the high-fat diet-induced obesity (DIO) model in C57BL/6 mice has been widely recognized as an obesity model driven by a dietary mechanism [12, 13].