The obese gene product leptin, exclusively expressed in white adipose tissue constitutes the most essential link of the feedback loop maintaining energy balance by signaling to the hypothalamus centers. Leptin expression is increased in obese rodents and humans and regulated by feeding, insulin, glucocorticoids and sex hormones. Men have significantly lower serum leptin levels than women at any given measure of obesity. Neither ob gene mutations nor leptin receptor mutations seem to be responsible for human obesity. Obese humans are probably leptin-resistant due to defective post-receptor signaling.

Keywords: Obesity, adipocytes-metabolism, lepid