FNDC5 and obesity due to melanocortin 4 receptor deficiency: The aim of our study was to determine the concentrations of Irisin and FGF-21 in children and adolescents with overweight and obesity before and after one year of a life-style intervention program of diet and physical exercise, and to explore the impact of BMI reduction on the concentrations of Irisin, FGF-21, and other cardiometabolic risk factors in these subjects.