TLR4 and obesity due to melanocortin 4 receptor deficiency: High-fat diet is also associated with alterations in gut permeability leading to the instauration of a state of chronic low-grade endotoxemia (presence of lipopolysaccharide, LPS, in the blood) that is believed to contribute to obesity-related inflammation by the activation of systemic macrophages through the binding of LPS on TLR4 (68, 69).