From fries to soda, these fast-food items hijack your brain's pleasure center and make you crave them nonstop.

There are plenty of exciting vegetarian options at the biggest fast-food chains. Be it the vegetarian versions of their main dishes or specialized items, there is something for everyone.

I ordered grilled cheese sandwiches at Sonic, Five Guys, and Shake Shack to see which fast-food chain has the best offering ... twice as many new menu items this year. Just don't get too attached.