There are allot of resturants that use added sugar in there tuna salad. Some people also use Miracle Whip instead of mayo. Also it would depend on the type pickle they use if they use a sweet pickle or sweet pickle relish that is going to add allot of carbs right there. I would deffinantly ask them how they make there tuna salad and then decide what to have. You are always safest to make it on your own. How I make my tuna:
1 can tuna in oil (drained)
1 can tuna in water (drained)
2 eggs
chopped dill pickles
chopped celery
chopped onion
mayo
salt and pepper
I am sorry I don't messure my pickles and small ingredients. I love tuna though sometimes I shred some lettuce real fine and chop a small tomato and mix it right in the tuna and then just enjoy.