I bet you anything the lady was frustrating the shit out of the doc. He's a DR, if he wants to call eating healthy a diet, then it's a diet. The fat lady can call it whatever she wants when she goes home if it soothes her bloated ego.
She probably kept BALKING at the things he was telling her she could and couldn't eat.

Gastric Bypass won't help if you don't change your eating habits. You'll lose weight, but then start gaining it back. Why go through a surgery that could kill you, if you can't deal with a DIET? You could run even MORE risks by gaining weight after such a surgery.