Of all the choices out there, Tuna is largely regarded to be the smart one. Why? Well, for starters, it's fish, which means that it's naturally lower in fat than other meats and it has essential fatty acids. And one of America's favourite ways to eat tuna (particularly for those of you who are turned off by seafood) is in a sandwich form--think either a tuna salad sandwich or one of my favourite, a tuna melt.

But here's something to ponder? Is tuna with mayo and cheese still just as healthy as fish on its own? That's a no-brainer: absolutely not! Still, how many calories can a bit of mayo add? What do you think? Does a tuna melt pack a calorie punch or is it a good way to get your protein in?

The correct answer is 2090 calories -- Gah! And if that's not shocking enough, it has 175 g of fat, according to the Quiznos website (it's true -- make sure to select a large sandwich with cheese and dressing.)

The moral of the story? Don't be naive -- do your nutritional research before eating out or--better yet--eat at home. When I get a craving for tuna, I make a tuna salad sandwich using a dash of olive oil, a squeeze of lemon juice, some black olives, chopped celery and freshly ground pepper. Or if I'm craving something a bit creamier, I use some low-fat cream cheese instead of mayo. Both methods are scrumptious, and not frighteningly bad for you either!

Oh, and be careful about eating too much tuna -- all that mercury can add up.

Want to know more shocking fast food secrets? Check out AOL Body's Worst Fast Foods in America feature.