INS and obesity due to melanocortin 4 receptor deficiency: Notably, there are various factors recognized to trigger insulin resistance: for instance, obesity [27,33,34,35,36], critical hyperglycemia [7,37], low-grade inflammation [34,36], the overproduction of reactive oxygen species (ROS) [37,38], mitochondrial dysfunction [39,40], impaired insulin signaling pathway [41], short-chain fatty acids (SCFAs) [42], and amino acids [2,4,40,43,44].