Endurance Training
This question depends on the goals your are trying to achieve. So the first question I ask is, "what are your goals?"
weight loss?
performance?
muscle gain?
maintenance?
The basic guideline I give my endurance athletes to follow is:
55% carbs
30% protein
15% fat
I will figure out the amount of calories a person needs depending on their weight, their body fat %, their activity level, their gender, and then of course their specific goals. So it varies from time to time like Matt said.
We need good complex carbohydrates as our main source of fuel during our workouts. We need good quality proteins to help us maintain our lean muscle mass and assist in the recovery of our musculature after intense training days. We need good sources of fat to keep our immune system strong and healthy.
Now, depending on the distances you are training for, your calories and nutrient breakdown will differ. Of course, the longer the distances you are competing at, you need more calories and more carbohydrates. The smaller distances, you do not need as many calories or carbohydrates. If your goal is all about performance, then you need to eat good complex carbs (whole grains, fresh fruit/veggies) all day long. This will keep your glycogen tank at a full level, so when you go and train, you will maintain a high level of energy, as long as you fuel yourself during your workouts.
I get clients that talk to me about weight loss and competing in endurance events and it is a very fine line that they must follow. During the week, when their schedule entails long workouts, you must eat sufficient amount of calories so you are fuelled during those workouts. When your workouts are less intense, you must cut calories on those days, so you can still maintain your energy but also lose weight. It goes back to the caloric deficit one must follow in order to lose weight. But you do not want a caloric deficit when you know you have a long workout in two days.
Everyone here should listen to their own body. Performance nutrition is so individualized. What works for somebody might not work for someone else. Try things out in training and see what works for you. If you stick to a balance nutrition plan and stick to eating fresh healthy food, you are on the right track. Just be consistent. Try writing down your foods for a few days and break it down and see where you have imbalances. It will help you get your nutrition down and in the end increase your performance.