Timing is everything when it comes to eating and working out. If you're too full, you get cramps, and if you're too hungry, you can't work your hardest. Keep pre-workout snacks, eaten 30 to 90 minutes prior to exercise, mostly in the carb family. These foods should be easily digestible and should contain about 40 to 100 grams of carbs with a low amount of fat. It's also a good idea to keep the fiber content to a minimum since high-fiber foods can be difficult to digest.