FAAH and obesity due to melanocortin 4 receptor deficiency: Differences in fatty acid amides may be linked to fatty acid amide hydrolase (FAAH) as polymorphisms of FAAH genes have been linked to obesity and insulin resistance [48] and endocannabinoid system-related genes (of which FAAH is one) have been shown to be effected by insulin dysregulation in adipose tissue [49].