I think that you have to figure that our through experimentation. For example, two years ago I would have had better performance on long steep hikes with a heavy load on the pack if I ingested a lot of carbs. Now.. I do *much* better and feel great with minimal carbs, and extra fat. Minimal = under 20. My body has adjusted to prefer fat for fuel, over time, if you choose, yours might as well... but obviously it's individual.