INS and obesity due to melanocortin 4 receptor deficiency: While it is well established that dietary long chain saturated fatty acids cause insulin insensitivity and obesity [7], there is some debate as to the role of lipid induced increases in gut permeability and subsequent leakage of gut bacterial lipopolysaccharide (LPS) [8], as opposed to the role of lipid overload and ectopic fat deposition [9], [10] in obesity related inflammation.