Fat experiences

Just casually blow it off. "I don't want to do that right now" "Naa, diets never work long term anyway" or any similar ways of just rolling those comments aside. Then change the subject.

Like

"Yeah, don't want to do that right now" "So, how is cousin xxxx doing these days?"

And it helps to be doing things with the rest of your life. If you are getting good marks or wirking tough hours or really involved in community theater or are volunteering for a cause you are pationate about, or... ,

Then your story becomes more about that than about you getting fat, and your weight becomes more of a side note.