STAT3 and obesity due to melanocortin 4 receptor deficiency: Recent studies have shown that obesity, a chronic low inflammation state [9–11], upregulates inflammatory cytokine such as interleukin6 (IL-6), then promotes the expression of hepcidin by activating the Janus kinase - signal transducer and activator of transcription-3 (JAK2-STAT3) signal pathway [12, 13] .