CCL2 and obesity due to melanocortin 4 receptor deficiency: MEF explants secreted high levels of several visceral‐associated inflammatory cytokines thought to be important for the negative adipose–muscle signalling in obesity, notably interleukin 6 (IL‐6), monocyte chemoattractant protein 1 (MCP‐1), tumour necrosis factor α (TNF‐α) and IL‐1β (Deng & Scherer, 2010) (Fig. 3B).