You can always ask if you are allowed to leave for meals. I had a workshop one Saturday and asked our principal (I'm a teacher) if we would be allowed to leave even though they were ordering in a super long sub sandwich. I told him I am low carbing. He said we would be free to leave.

The next day when I got to the workshop he had gone and gotten a veggie tray and a bunch of nuts so that I could snack too. I ended up staying and just eating the insides of the sub.

You never know unless you ask right.