What you choose to use as your fuel, how much, and when plays a crucial part in determining your performance. Follow these simple guidelines to help optimize your performance:

Consume no more than 280 carbohydrate calories per hour because that is the most the liver can return to the energy cycle. This figure is for a 160 pound athlete. The amount varies for larger or smaller athletes. The ratio is approximately 1.74.
Avoid drinks and gels made with simple sugars such as glucose, fructose, lactose and sucrose. Look for the more complex carbohydrates from maltodextrin (glucose polymers). If you do use simple sugars, dilute them.
For exercise over 2 hours, start providing some protein in the fuel mix to satisfy the5-15 the body requires.