Studies have shown an amelioration of the development of diet-induced obesity in male mice knockout for Ccr2 [76,77], and of obesity-associated metabolic complications in genetically obese (db/db) male mice treated with a pharmacological inhibitor of CCR2 [78], suggesting CCR2 may influence the development of obesity. This evidence concerns the gene CCR2 and obesity due to melanocortin 4 receptor deficiency.