Dogmama, I don't know what kind of mileage you put in on a weekly basis but I'll share what I did during Phase 1. The diet is low carb for only the first two weeks which is fine for about an hour's road ride at moderate levels (for me). Anything longer or more intense required more glycogen than Phase 1 can supply. The glycogen stores are pretty depleted during this time.

Starting with lunch the day before a long ride, for me Friday lunch, I would eat pasta or rice and stay with a fairly high carb diet through Sunday lunch. I could ride longer and with more intensity (for instance mtb rides) without problem. I would go back to the Phase 1 diet at Sunday dinner. Due to this I extended Phase 1 to three weeks. This modification worked really well for me. I have a friend who tried a pure Phase 1 approach but for some reason insisted on no carbs at all (I don't think he even ate vegetables which isn't part of the plan) and, in his words, "just about died." I tried to get him to understand the relationship between carbohydrates and glycogen stores but he wouldn't and now bad mouths the diet. Agatston even states briefly somewhere in the book that endurance athletes need to be aware of this issue.

The first part of the book is the educational part while the second half is recipes. An easy read and very educational - stuff we all should know. It is very little effort to get up to speed on Agatston's reasoning and make your own decision.