Ultimately we should learn to eat according to hunger. Most people do that anyway although they may occasionally have a pork-out or put themselves temporarily on a diet to lose a few pounds for some reason best known to them. For people with eating disorders, however, the idea of eating according to hunger is novel. They would tend to eat or abstain when they are angry, lonely or tired rather than when they are hungry or full. For them the concept that fat comes from food is far from being a statement of the obvious: it is a fundamental challenge to their personal philosophy.