Male mice lacking AIF1 showed relative resistance to hyperglycemia and a high-fat diet, and their adipose-tissue levels of norepinephrine (NE) were higher, due to less monoaminoxidase A activity and NE clearance by macrophages, suggesting that AIF1 silencing protected against obesity [163]. Here, AIF1 is linked to obesity due to melanocortin 4 receptor deficiency.