Body weight and body fat content are well regulated. In humans, body weight tends to remain within a relatively narrow range, despite large day-to-day fluctuations in the amount of food consumed. Although major changes of body adiposity can be induced in humans by restricting energy intake or by overfeeding, body weight and adiposity return very close to baseline levels when ad libitum feeding is resumed. Although there are many peripheral signals that can contribute to feeding behavior and body weight regulation, it is important to recognize that short-term and long-term food intake and energy balance are regulated through distinct, but interacting, mechanisms.This review discusses hormonal and related Sateity signals generated as food is being consumed and upon adiposity signals related to the amount of fat stored in the body that influence food intake and body weight.