TLR4 and obesity due to melanocortin 4 receptor deficiency: One is the biomechanics stress in obesity3, and the other is obesity-induced low grade inflammation4, characterized by activation of proinflammatory signaling pathway (TLR4, NF-κB, JNK, etc) and elevation of proinflammatory cytokines (IL-6, IL-1β, TNF-α, etc) in multiple organs and tissues5, 6, 7, 8.