a peanut butter on whole wheat sandwich is great before a cardio workout...i have one about 45-60min before i go to ju jitsu/cardio kickboxing. i find that the more protein i eat, the fuller i am throughout the day...i wouldn't be too concerned about the fat that's in the peanut butter -as long as your not sitting on you ass eatting it right out of the jar...be sensible about the amount you put on there...try it