Drink some extra water.
Follow the plan.
Have a plan for situations like this. (A lot of us bring our own food or have emergency stash in purse, car, etc. Some folks have even called ahead-of-time to determine what will be served so a plan can be formulated if the food won't "work")
Some people will say cut restricteds but what is done is done.
Losing weight is hard. Maintenance is hard. Being fat is hard. Pick your hard. (-Ishbel)