Heidi Montag's plastic surgeon Frank Ryan gave an interview to Good Day LA. He says that Heidi, "like many other young men and women today, just wanted to improve her appearance." So that's why he turned her into an alien.
Dr. Ryan also claims he was blindsided by the People magazine story. He thought he was getting a sidebar! He didn't get a sidebar! Waaah waaah. Guess you're going to have to find some other way to use mentally unstable Hollywood starlets for fame and fortune.