"fatty" and "fatso" are a couple of examples. But as BritishEnglishCoach already mentioned, they are all very derogatory. However, if you are talking about the issue of being fat (obesity) and want to speak of such a person, you can say "an obese person" or "a heavyset person". For example, you can say: "An obese person is more likely to have high blood pressure or diabetes."

Yes, there are many. But I can't think of any which are not derogatory.