Cause for the Hunger?

In T.C. Boyle's novel World's End, Harmanus van Brunt is beset by an insatiable hunger so intense that he eats in one day almost all of the food his family had saved for the long 17th century New York winter. A similar fate besets his son Jeremias in his own adulthood. I was curious as to whether this was a documented disorder that could explain this behavior or whether this was a syndrome made up by T.C. Boyle for literary purposes.

I found only one genetic disorder whose main symptom was insatiable hunger. Prader-Willi syndrome is a mutation that causes a problem in the hypothalamus of the brain so that the feeling of being full never registers. This would describe the symptoms of our characters, except that Prader-Willi syndrome is normally observed from very early childhood. Whereas our Jeremias and Harmanus both had eating binges that started abruptly after a lifetime of normal eating habits, victims of Prader-Willi spend their entire lives battling the illness.

I couldn't find any real-life examples of Jeremias' and Harmanus' disease, but I challenge the members of our class and the readers of this blog to find a documented case, either in a story or in scientific literature.