Primal Endurance puts a huge emphasis on the amount of carbs you take in. As the book states the amount of carbs is dependent on your goal. If you goal is fat loss than you will have different carb intake requirements than someone who wants to maintain their current body composition. Regardless of what your goal is you need to make sure you feel right. If you start to eat low carb and your performance decreases or your energy suffers than you might be to low carb. It is important to remember that everyone’s body is different. Some people might perform fine with a certain level of carbs but someone else with the same goals might not. In this article Chris Kresser explains that you might be lower carb than you might think. It is worth reading if you are just starting out on your low carb journey.