I travelled recently and had to deal with airport food and restaurants. I took along some snacks and found that in most restaurants the staff will gladly substitute extra veggies for the potatoes or rice. They'll leave off croutons on a Caesar salad and have your dressing on the side if you're concerned about the carb count. Water is available everywhere so you can keep up with this quite easily. My main problem was in airports where all the food is nasty. I stuck to decaff coffee and water and some peanuts. I survived and you can too. It just takes some planning.
Have a great trip and with a little forethought, you will have a wonderful time.

Cheers,
Lara