Consistent with previous findings in a large population-based cohort [27], we showed that BMI correlates negatively with serum IGF-1 (also below the BMI obesity threshold), suggesting that the common exclusion of individuals with obesity (BMI > 30) [9,26,40] might not be sufficient to account for the effect of this factor on IGF-1 levels [40]. Here, IGF1 is linked to obesity due to melanocortin 4 receptor deficiency.