dr. mary brandt was hesitant about doing such a major and irreversible operation on a teen. >> i really didn't think it was a good idea. metabolically changing a teen made no sense. this is the first generation that's not going to outlive their parents. >> that's a shocking notion. >> reporter: have you thought how your face is going to look? >> i'm going to have a slim face. i'm going to have surgery in 3 hours and 48 minutes. it's been 48 minutes now. he's really hanging in there. >> there you go. >> reporter: the procedure takes about two hours, completely rewiring the digestive system and reducing the stomach to the size of an egg. nick is so confident that he will now be able to lose weight quickly that he makes a bold bet with me. where do you think you'll be in september. >> i'm going to push myself and say i'm going to lose 60 pounds. >> reporter: 60? in six weeks you're saying? >> yeah. >> reporter: it's tough as nick adjusts to eating tiny portions. look at you, how good you look. seven weeks later, he's come to new york city. you look amazing. >> thank you. >> reporter: it's obvious