With regard to obesity, studies show that NADPH oxidase activity/expression is increased in laboratory animals given high fat diet [13], [14], and further indicate that diet-induced NADPH oxidase activity mediates obesity-related cytokine/chemokine release as well as insulin resistance, hyperlipidemia, and liver steatosis [14]. Here, FMO5 is linked to obesity due to melanocortin 4 receptor deficiency.