TNF and obesity due to melanocortin 4 receptor deficiency: Poor adipocyte metabolism has been linked to both obesity and T2DM, leading to an increase in lipolysis and FFA levels and an elevation in the expression level of inflammatory cytokines such as tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) from activated adipose tissue macrophages (41–43).