There are lots of sugar substitutes if they will eat that. I have a friend who makes a delicious sugar-free cheesecake, but it is chock full of artificial sweeteners. I am 100% zero sugar right now including no artificial sweeteners (paleo) and to be perfectly honest, it's extremely difficult to eat like everyone else. Sugar is in EVERYTHING. Did you know that bacon has sugar in it? Or mustard? I didn't before starting this!

Anyone who is avoiding sugar of all types including artificial sweeteners will just forgo eating anything sweet. For me, I do eat fruit. So when we have big potlucks at work, I stick to fresh fruit. I do not hold it against anyone who doesn't accommodate my needs (unless it were MY birthday, of course!). I doubt your coworker would either.