fuel is in fat, protien and carbs, not just carbs. carbs are more readily converted to glycegen which is the actual fuel your muscles use, but the other fuels also get converted glycogen for use. I find that at about 50-60g carbs per day is sufficient for triathlon training. Of course everyone is unique so you will have to find the level that works for you. But it sems 50-60 is about what most athletes on here find keeps them from bonking.