I don't think the glycogen aspect is cut and dried. I've had great success with no carb fuelling. I know a national champ and record holder that is the same and on HFLC. I also know a high level M4 master that is a dribbling mess without carbs. His body is different to ours. Up until I went HFLC I NEEDED protein isolate to recover from hard efforts. It made a big difference to my recovery. Since HFLC I have zero problems with recovery aside from some cramping early in my HFLC journey. Increasing my magnesium intake seems to have fixed that issue. I no longer take any protein supplements and I am the strongest I have ever been on the bike.