Most of the energy your body uses during a long run will come from carbohydrate. Ideally, 2-3 hours before an endurance event, such as a 15+ mile run, a high carbohydrate meal would be eaten. This includes about 80-100 gms carbohydrate. For example, 1 c pasta, 1/2 c red sauce, 1 piece of fruit, 1c milk, 1 pc of bread with pb&j. Then, eat or drink ~15 more gms carb 20-30 minutes before the run. If the run is first thing in the morning, then eat the high carb meal the night before & wake up at least 30 minutes before the run to have at least 15-20 gms carb. This could come from fruit or 100% fruit juice, bread, rice, pasta, milk, cereal, or gatorade or gatorlode. Be sure to bring high energy snacks with you on the run. For example; sports drink, dried fruit, bread, &/or energy bars work well to rejuvenate. After about one to one & 1/2 hours, it is important to replenish glycogen stores. So, eat ~15gm carb after 60-90 minutes. This is equal to 1 piece of bread, 1/3 cliff bar, 6oz juice, 1 piece of fruit (size of baseball). Then, after your run, eat a balanced meal. One that focuses on grain, veggies, protein, and fruit. Stay hydrated by drinking > 2.5 L of water not including your run. If your hungry, eat! Good luck!