Inflammation, which becomes chronic with the secretion of inflammatory cytokines such as tumour necrosis factor-α (TNF-α) and interleukin-6 (IL-6) in excess in the adipose tissue that increases in obesity, causes pathological changes in insulin-sensitive tissues and β-cells, leading to disruption of metabolic regulation29. Here, IL6 is linked to obesity due to melanocortin 4 receptor deficiency.