FNDC5 and obesity due to melanocortin 4 receptor deficiency: In another study, Tung et al. treated obesity rats with 10, 20, and 50 mg/kg BW Mel for 8 weeks, and found that Mel reduced BW gain and increased the circulating irisin concentrations; an increased number of brite/beige adipocytes was observed in the inguinal WATs [51].