Hunger and satiety as conditioned reflexes.

How can a weak or biased appetite control mechanism arise and make a contribution to an individual's weight problem? In principle, physical pathology could occur, for example in the peripheral or central nervous system mechanisms critical to perception or action relative to nutrient needs. However, it is quite unnecessary to expect an individual's physical endowment to be outside the normal range if the control of eating is a problem. Unfortunate experience can create weaknesses or biases in the functioning of entirely normal neural and extraneural processes.