The anti-obesity effect of green tea is mainly attributed to catechins, in particular EGCG, which exhibits its anti-obesity effects through several mechanisms including suppression of adipocyte differentiation and proliferation, inhibition of fat absorption from the gut, and suppression of catechol-o-methyl transferase (COMT), an enzyme that inhibits fatty acid oxidation in brown adipose tissue. This evidence concerns the gene COMT and obesity due to melanocortin 4 receptor deficiency.