MC4R and obesity due to melanocortin 4 receptor deficiency: Western diet (WD)-fed MC4R-KO mice and Gubra-Amylin non-alcoholic steatohepatitis (GAN) diet-fed mice models have been reported to highly resemble human MASH in terms of obesity, dyslipidemia, insulin resistance, liver injury, steatosis, and fibrosis21,26,27.