A good diet won't turn you in to Superman but it will make sure that you play to the best of your ability throughout the whole match because:
Energy stores will be high enough to last the full 90 minutes. Concentration will be better There will be less of a chance of getting injured
How tired you are depends not only on your fitness but also on what foods and fluids you have taken.Scientific studies show that players who eat a good diet for energy run longer,sprint more,keep their concentration longer,and are less likely to get injured.
Players at Academy level are increasingly playing with the benefit of a good diet and dietary sipplement.It is really easy to eat well.Why not score one over your opponents first?