Binge eating disorder is a psychiatric disorder in which a subject:
periodically does not exercise control over consumption of food
eats an unusually large amount of food at one time (on average, 1500 calories).
eats much more quickly during binge episodes than during normal eating episodes
eats until physically uncomfortable
eats large amounts of food, even when they are not really hungry
always eats alone during binge eating episodes, in order to avoid discovery of the disorder
often eats alone during periods of normal eating, owing to feelings of embarrassment about food
feels disgusted, depressed, or guilty after binge eating
Binge eating is an element of another eating disorder, bulimia nervosa. The formal diagnosis criteria are similar: at least two binges per week for an extended period of time.[1] In binge eating disorder, by contrast, the person does not purge, fast or engage in strenuous exercise after binge eating. Additionally, people with bulimia are typically of normal weight or may be slightly overweight (the purging, etc., have little to no effect on the subject's body fat), whereas people with binge eating disorder are typically overweight or obese.
Binge eating disorder is similar to, but it is distinct from, compulsive eating. People with binge eating disorder do not have a compulsion to overeat and do not spend a great deal of time fantasising about food. On the contrary, some people with binge eating disorder have very negative feelings about food. As with other eating disorders, binge eating is an expressive disorder - that is, the disorder is an expression of a deeper psychological problem.
It is actually hotly contested whether binge eating disorder has its own diagnosis. Some believe that it is a milder form, or subset of bulimia nervosa, but others argue that it is its own distinct disorder. Currently, the DSM-IV categorizes it under Eating disorder not otherwise specified (EDNOS), simply stating that more research is needed.

Source, Links and More Info:
http://en.wikipedia.org/wiki/Binge_eating_disorder