C1QTNF6 and obesity due to melanocortin 4 receptor deficiency: This signal(s)—in the form of a secreted factor or metabolite—likely exists, as we have previously noted that Ctrp6 expression in obesity can be downregulated back to normal levels if mice are subjected to a diet reversal (i.e., switching from a high-fat to a low-fat diet after obesity induction) (26).