ER stress contributes to the pathophysiology of many diseases including ageing, tumorigenesis and metabolic diseases such as obesity and type 2 diabetes mellitus (T2DM).[1, 2] An increase in circulating saturated fatty acids, such as palmitate, characterise metabolic diseases including obesity, T2DM and dyslipidemia.[3, 4] These elevated fatty acids promote metabolic dysfunction through a process called ‘lipotoxicity’ in insulin‐responsive tissues. The gene discussed is INS; the disease is obesity due to melanocortin 4 receptor deficiency.