Which of the following conditions is thought to contribute to the development of obesity?

ANS: B
Leptin, a product of the obesity gene (Ob gene), acts on the hypothalamus to suppress appetite and functions to regulate body weight within a fairly narrow range. Leptin levels increase as the number of adipocytes increases; however, for unknown reasons, high leptin levels are ineffective at decreasing appetite and energy expenditure, a condition known as leptin resistance. Leptin re-sistance fails to inhibit oriexigenic hypothalamic satiety signaling and promotes overeating and excessive weight gain. Insulin becomes resistant, not present in excess. Leptin resistance, not ad-ipocyte failure, leads to obesity. Malabsorption does not lead to obesity, but primarily to weight loss.