So where do you draw the line? Can I tell a smoker I can't stand the smell of their stale smoke so please move because your personal choice is offending me.
I actually agree that you should be able to. Yes its their personal and lifestyle choice, but it is also mine to not smoke and have to smell that. But unfortunately i am too polite to even request the person who blows smoke into my face in a public place to stop. As onyx said sometimes you just hold your breath and bear it.

I dont think M was having a "weight" issue discussion, more so than a "personal space" discussion. As others have said, if you are invading someone else's space (no matter size, shape, form, gender etc) you're the one at fault, what gives you more rights than the other person. Its part of good manners.