To then reveal the exact role of myeloid NADPH oxidase in the pathophysiology of obesity, C57Bl/6 (NOX2-FL) and myeloid-deficient NOX2 (mNOX2-KO) mice were given high fat diet for 16 weeks, and subject to comprehensive metabolic, behavioral, and biochemical analyses. Here, FMO5 is linked to obesity due to melanocortin 4 receptor deficiency.