As well as going to the gym regularly, I have been participating in some long runs (about 12 miles), and have noticed a major difference when I have a slice of toast made with multi seeded bread and spread with peanut butter about two hours before the run. I have noticed also that I have more energy when I do this before going to the gym, although I mainly go to the gym straight from work, so this isn't always possible. I believe this is because the carbohydrates provide energy and the nuts and seeds from the bread and peanut butter is slow releasing energy. The advice I have had though, is carbs before exercise and protein afterwards. Hope this helps.