I use to say to some people "what do you expect I am x weeks pregnant" in a laughy voice. Sometimes I would say "yeah i really should lay off the dounuts i am starting to look like i am pregnant" Then one one occasion I was in a bad mood and I coped a comment from a heavier person and I just said back "at least I have an excuse" - mind you I practically ran away after that for fear of being beaten to a pulp