Indeed, subsequent studies have shown that other proinflammatory mediators such as interleukin- (IL-) 1β, IL-6, interferon- (IFN-) γ, ceramides, prostaglandins, and lipopolysaccharide (LPS) from the membrane of gram-negative bacteria residing in gut microbiota, among others, are also involved in the development of obesity-associated insulin resistance [34–36]. This evidence concerns the gene IL6 and obesity due to melanocortin 4 receptor deficiency.