Many of the calories in fast food, often come from the cheese and the mayonaise. Cheese on a fast food burger is about 50 calories per slice, so those 2 small slices of cheese on a burger from McDonald’s, Wendy’s or Burger King add 100 calories. Mayonaise is about 100 calories per tablespoon, so the secret sauce on most burgers adds another 100 calories. The tuna salad and the seafood salad are two of the highest caloric sandwiches you can get at Subway. You’re already pitching the bun, but hold the cheese and mayo, if you want to lose weight.