In obesity, it has been found that a shift in the activation state of macrophages in AT from M2Ф in lean animals to M1Ф [143], upon the activation of MФ, secretes numerous cytokines and chemokines, such as TNF-α, IL-1, IL-6 and chemokine MCP-1 [159,160]. This evidence concerns the gene IL6 and obesity due to melanocortin 4 receptor deficiency.