In obesity, there is an increase in pro-inflammatory cytokines, such as TNF-α, which can lead to ROS accumulation, inducing the expression of pro-oxidant enzymes (e.g., NADPH oxidase) and reducing the expression of antioxidant enzymes (e.g., catalase) [74]. Here, FMO5 is linked to obesity due to melanocortin 4 receptor deficiency.