Endurance athletes engaged in early-season training are usually concerned with gaining fitness while they simultaneously lose a bit of weight. This is a good time to get down to race weight, but it's important to provide your body with the proper nutrition and energy in the process so you can perform at your best. Pre-workout nutrition should consist primarily of carbohydrates, with a little bit of protein. Carbohydrates fuel your body's performance during exercise.
During a long workout, you should consume some carbohydrates as fuel. Sports drinks, bars or gels are all good sources. The rule of thumb is 30-60 grams per hour. After your workout, it's important to replenish what your body has used as soon as possible. The best time to consume foods high in carbohydrates is 30-60 minutes after exercise.