Although some adipokines, including, e.g., leptin, adiponectin, ghrelin, resistin, or interleukins have been studied extensively, the role of many others, including follistatin-like 1 (FSTL1), which has also been suggested as linked to obesity, remains unclear [2, 3]. Here, FSTL1 is linked to obesity due to melanocortin 4 receptor deficiency.