There is almost always a grilled chicken salad at a fast food place. Generally, the chicken has added sodium, so you don't want to do it all the time. For example, the McD's southwest grilled salad without tortilla chips has veggies, chicken and black beans/corn (which would cover your starch). At other places, if you packed melba toast or low carb tortilla to go with your salad, you'll be good to go.
If there is no salad, I would order a grilled chicken sandwich with no bread. Is it the most attractive dinner out there? No - but it's life and you won't have to pay the carb monster the next day. Drink plenty of water to flush the sodium. Many places have water fountains where you can refill your bottle - or maybe take a gallon jug.
Debi in FoCo, Co