Originally Posted by
MoAlpha
Fat cannot replenish glycogen.
Fat absolutely is one of the "fuels" that are used by the liver (primarily) and kidneys (lesser extent and increasingly when fasting I think) for gluconeogenesis. Any non-carb source can be used: it's how non-carb-eaters keep their blood sugars up.
Acetone from keytone bodies can also be used as a substrate for the creation of glucose.
I do all my riding fasted and never run out of glucose. Haven't "bonked" once since I stopped eating carbs.
I am curious though about the impact of ingesting carbs ahead of high-output ride sections like hills or sprints - but I'm most specifically interested in the timing: I would want to know exactly *when* to take them, although I suspect that even with experimentation I would never really know.