Apples are great snacks, and they're often paired with peanut butter or sliced cheese for a well-rounded energy boost of carbs, fat, and protein. The apples are an important part of the equation, as they are low-calorie and full of vitamins, nutrients, fiber, and lots of other good stuff. It's the other half that's always the problem, as eating too much peanut butter or cheese is an easy way to polish off a boatload of calories and fat in one sitting.