A runner should consume complex carbohydrates in addition to lean proteins such as fish and healthy fats such as nuts before a long run. Carbohydrate sources that help provide energy to a runner include foods such as bagels, bananas, pasta and oatmeal.
Fruits, vegetables and whole grains are complex carbohydrates that are good to eat before a long run. Low-fat dairy products and eggs are also suitable.
The body requires carbohydrate-rich food sources to produce energy during exercise, and it converts them into glycogen, which is stored in the muscles and the liver. Adequate glycogen stores prevent the body from using protein as a primary energy source, and this is beneficial because proteins are important for rebuilding and repairing muscle after exercise.