Previous studies have found that in adipose tissue, the key event in insulin resistance is the activation and accumulation of proinflammatory macrophages, which influence the metabolic status of adipose tissue parenchymal cells through the release of cytokines, such as IL-6 and TNF-α, which induces impaired insulin metabolism pathways and abnormal glucose metabolism, providing a potential cause of obesity-induced insulin resistance [106, 110–115]. Here, TNF is linked to obesity due to melanocortin 4 receptor deficiency.