FNDC5 and obesity due to melanocortin 4 receptor deficiency: An intriguing finding by injecting mice with 500 μg/kg irisin daily for 2 weeks reduced the body weight and improved glucose homeostasis through increasing the expression of UCP-1 gene which helped in browning white adipose tissue, this could be a preventive countermeasure for obesity and associated type 2 diabetes [11].