I mostly hike but in nicer times of the year I cycle commute. I noticed that my ability to keep up with my friends hiking up mountains really suffered for a few months. Eventually I adapted and was able to hike long distances without food, still a little slower, but at least I didn't feel totally wiped out. Eventually I was able to fully keep up and get to the top before my friends. And then even further along in my journey I added back in more carbs and am able to go even faster. I think it's beneficial to force your body to make the adaptation, but the carbs do help performance. The nice thing about making the adaptation for me has been that even though I eat more carbs daily, I can still enjoy not needing to eat on a long hike because I've maintained that metabolic flexibility to access my body fat for fuel. I don't crash anymore like I used to.
Female, 5'3", 49, Starting weight: 163lbs. Current weight: 135 (more or less).
Starting squat: 45lbs. Current squat: 160 x 2