From personal experience: I wouldn't even discuss it with anyone who's not already actively involved in losing weight. Several reasons to that:
1) Especially when we start changing our eating habits, we feel like discussing all of it, and people who aren't trying to lose weight aren't really interested in that to start with.
2) It quickly becomes old when everyone and their dog asks you "should you be eating that?", "aren't you on a diet?", and so on.
3) If you give up/get into a slump, it's all the more fuel for other people's remarks. And some will always secretly rejoice to see another person stumble and fall.
4) Telling a person who's also overweight might make him/her think you're criticizing/judging.
My piece of advice here: just do it. Let it speak for itself. If you say no to candy or chocolate or second servings, and people ask you "why", just say that you're not hungry anymore, don't feel like eating that now, whatever. It'll be much less of a bother in the long run, you won't feel under scrutiny, and you'll be able to do things
your way, at
your own rhythm, without everyone chiming in (often with contradictory advice...) all the time.