I feel really bad for you and can understand your difficulty! That's quite a temptation you have going on. My first thought it to get a different job. If you totally are not willing to work anywhere else than the only thing I can think to tell you is to bring lots of ibs safe snacks with you to work. I don't know if you like smoothies or not (I love them) but you could sip on one(or two)while you work. That might help chase any hunger pangs away you are having for McDonald's food. Don't let yourself get hungry-- satisfy yourself with the foods/drinks you bring from home.