Compulsive overeating is characterised by an addiction to food. An individual suffering from compulsive overeating disorder engages in frequent episodes of uncontrolled eating, or binging, during which they may feel frenzied or out of control. They will eat much more quickly than is normal, and continue to eat even past the point of being uncomfortably full. Binging in this way is generally followed by a period of intense guilt feelings and depression. Unlike individuals with bulimia, compulsive overeaters do not attempt to compensate for their binging with purging behaviours such as fasting, laxative use or vomiting. Compulsive overeaters will typically eat when they are not hungry, spend excessive amounts of time and thought devoted to food, and secretly plan or fantasize about eating alone. Compulsive overeating almost always leads to weight gain and obesity, but not everyone who is obese is also a compulsive overeater.
In addition to binge eating, compulsive overeaters can also engage in grazing behaviour, during which they return to pick at food over and over throughout the day. This results in a large overall number of calories consumed even if the quantities eaten at any one time may be small. When a compulsive eater overeats primarily through binging, he or she can be said to have binge eating disorder. Where there is continuous overeating but no binging, then the sufferer has compulsive overeating disorder.
Left untreated, compulsive overeating can lead to serious medical conditions including high cholesterol, diabetes, heart disease, hypertension and clinical depression. Additional long-term side effects of the condition also include kidney disease, arthritis, bone deterioration and stroke.

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