I have the same problem. I am skinny (5'7'' and 110 lbs.) and always get comments about my weight. "Well, I can't friggin eat as much as you!!" is what i want to say.
The only comments I usually get at work about my eating restrictions are: "you poor thing" when we have a dairy eating party at work (read: cake and ice cream...) and "go girl! eat eat eat" when they see me snacking at my desk. How lame? Like my diet is anyone's business in the first place.
So good luck with all the hecklers. There are lots of those in life! My idea is that anyone who makes a disparaging remark about someone else is most likely doing it out of jealousy. Example: you're thin, they're not! So let THEM deal with their insecurities, and just know that you are a better person for not feeling the need to talk down to someone, or make someone feel like a freak for acting/being/eating a certain way.
More power to you for sticking to your diet and not eating a junky donut just because everyone else is!
-------------------- "I have no patience for lactose. And I won't stand for it." -Jerry Seinfeld