GDF15, also known as NSAID-activated gene 1 (NAG-1) and macrophage inhibitory cytokine 1 (MIC-1), is a stress response cytokine and a distant member of the transforming growth factor beta (TGFβ) superfamily (6) with well-documented roles in obesity and regulation of energy homeostasis (9), in addition to several conditions with an important inflammatory component (10). Here, GDF15 is linked to obesity due to melanocortin 4 receptor deficiency.