Studies in pre-pubescent schoolchildren (age 5–13 years) and male adolescents (age 13–17 years) demonstrate that these associations are not only observed in adults, reporting increased MIF levels in overweight and obesity in childhood and adolescence (32, 33), and showing positive correlations with waist circumference and BMI (33) in this study population as well. Here, MIF is linked to obesity due to melanocortin 4 receptor deficiency.