How do you feel the tough VO2 or threshold workouts not earring breakfast? I have been doing intermittent fasting for the past year with low carb life style. I never eat breakfast for zone 2 up to Sweet Spot workouts regardless duration. But when doing threshold workouts, I started to fail my workouts. Now I’m really conflicted if I should do carb loading the night before or not. The thing is I don’t know the reason I’m failing these tough workouts is because food or my FTP just set too high and my legs are not handling the intensity of the workout. I’m thinking is the latter. I really want to continue to be a fat burner instead of sugar burner. But reading all the articles, it seems most people say you need keep pumping carb to fuel intense workouts because Ketones can’t keep up the energy required for tough workouts.