Do the people at your staff meeting know why you've changed your diet? If they do, and they still carried on that way, then they're just a-holes. If they don't know, then it might help to explain it to one or two of them that you're closest to, and to include in your explanation that you're able to find something to eat in pretty much any restaurant you go to.

There will always be people who are unable to empathize with your situation and think you're weird or annoying because of your diet. Some of them won't have the good sense or manners to keep their mouths shut. Avoid them if you can. If you can't, shut them down by changing the subject. If they're really rude, just say "wow" and leave the room.