I disagree.  If he did, there is exactly zero chance he could have lost 77 pounds on his own before the surgery.  Also I highly doubt a doctor would do that surgery on someone with Prader-willi since there is a very high chance they will rupture their truncated stomach.  Also there is typically a cognitive issue with Prader-Willi that I don't see in this kid.  He's a bit awkward and childish, but I think that has to do with being isolated and sheltered since he can't do normal teen things.  He seems to be able to grasp what is going on and why.  He also seems to have a measure of self control.