He could be a sadistic Dr Kervorkin, who likes watching his patients die a painful slow death. Also the more fat someone is, theoretically the more visits they will book, and the more $$$ he can bill their insurance. I know a lot of doctors, and most seem to have an attitude of "fuck it" because people are so ridiculous and demanding, and its exhausting to care when your patients don't. I could definitely see some pulling this, and profiting off the general public's stupidity.