BDNF and obesity disorder: Mounting experimental evidence supports this association of Met variant with obesity: the derived Met allele reduces the expression of BDNF, which plays pivotal roles in the inhibition of excess calorie uptake (e.g. vigorous appetite, bad dietary behavior and sedentary lifestyle) and in the enhancement of energy expenditure (e.g. acceleration of brown fat metabolism and the degeneration of serum level of TG, TC, and free fatty acids and improvement of insulin resistance) [23, 28, 29].