Self-deprecatory remarks about a person's previous, overweight self. Or for that matter, current self. If you wouldn't say it about somebody else why be so hard on yourself? Also I think we can hit unintended targets, people will apply things you only meant for yourself to themselves.

This especially applies to people with like ten extra pounds to lose. Somebody's watching who has ten times that to lose, how are they supposed to feel watching you tear yourself a new one?