Increased ceramide [17], intramyocellular lipids (IMCLs) [18], diacylglycerol (DAG) [19, 20], and long-chain fatty acyl-CoA [21] levels have been negatively correlated with insulin action, depicting the importance of understanding the link between obesity and the lack of insulin response in skeletal muscle. This evidence concerns the gene INS and obesity due to melanocortin 4 receptor deficiency.