People who suffer from eating disorders tend to have a range of dysfunctional thoughts concerning their own body image: they are unable to evaluate their weight and body image objectively.

For this reason, these people spend much of their time trying to conform to a body ideal, an image, that often exists only in their minds and in reality is unachievable, because it is far from their physiological weight.

One theory about their motivation is that they begin their "rational" behaviours on weight control because it is easier to exercise control over one's body than to improve character features.

The most important psychological defect of people suffering from eating disorders is that they do not like themselves, and for them weight control becomes a means of overcoming this lack of self-esteem.

The behaviour, seemingly so strange, that these people exhibit is closely linked to this lack of self-confidence.

People with eating disorders think they are worthless (have low self-esteem, more) and so they must try to be special. They think they are bad and so they must always try to be good and understanding. They think that they lack self-control and so they must always try to exercise strict control on everything and everybody. They see themselves as ugly and fat, and so they try to overcome this by becoming as slim as possible. They do not accept half-measures, and when they get the idea of doing something they either do it completely or not at all. That is, they live in a world of extremes - one is either very thin or very fat.