Adam is a teenager with a huge appetite. he has an uncontrollable urge to eat large portions of junk food within very short intervals of time. he is embarrassed by his eating disorder and hence prefers eating alone. adam is most likely suffering from

Binge eating disorder

This is a life threatening but treatable eating disorder described by recurrent episodes of eating large amount of food usually eaten at short period of time. There is a feeling of loss of control during binge eating but also experience shame, distress, guild afterwards. Person with this type of disorder usually prefers to eat alone even when they are not hungry. This is also one of the most common type of eating disorder.