A good book to read is The Art and Science of Low Carbohydrate Performance by Finney and Volek. It gets pretty technical at times as they go into a lot of details about the science and the studies behind a lower carb approach. Another good resource is to look up Metabolic Efficiency and Bob Seebohar. I would look at these options as opposed to the off the counter stuff like the Atkins book just because they're addressed more around combining activity with diet. Essentially it's about training your body to burn fat as the primary energy source rather than carbs. There is some benefit to the approach for endurance based exercise (long distance bike rides) because when you can stabilize your blood sugar you don't go through the highs, lows, and crashes that go with trying to spike your energy with gu and sugary drinks. I think there's a lot of validity to it. However, going that route is a pretty complete and lifelong commitment.