Compulsive eaters and drug addicts frequently lie about their disorder.
When they say that they want to get well, they are influenced by their adult, mature self which realizes the sad consequences their eating disorder will have. At the same time, another part of their consciousness craves immediate satisfaction and the suppression of anxiety and psychic distress.
Thus, the same person can have two different personalities which struggle for control. Even while binge-eating, the adult part of her/his personality realizes that it is wrong. That gives the person even more anxiety, which causes the individual to eat even more in order to reduce the new anxiety. The secret of success in the struggle against compulsive eating is to learn to tolerate the unpleasant feelings instead of trying to smother them by continuing to eat excessively. This is a more difficult way, but in the end it gives lasting success.
A person with an eating disorder denies his abuse in the same way an alcoholic does. They are both prepared to lie not to miss out on the stimulance of the brain's center of pleasure and reward.