A study of the cellular composition of WAT in obesity revealed three populations of monocytes, including non-classical monocytes (FCGR3A, HES4) and classical monocytes: Mo-1 (FCER1A) and Mo-2 (CSF3R, FCAR, SELL) [111] (Figure 2). Here, FCGR3A is linked to obesity due to melanocortin 4 receptor deficiency.