Hunger is a feeling experienced when one has a need to eat food. Hunger is different from appetite, the desire (rather than need) to eat food. Satiety is the absence of hunger. The often unpleasant feeling of hunger originates from the hypothalamus releasing hormones that target receptors in the liver. Although a healthy, well-nourished individual can survive for weeks without food intake, the sensation of hunger typically manifests after only a few hours without eating and is generally considered to be unpleasant. - Source: Wikipedia