[zbtaylor1]

> First, as you might expect, aerobic and endurance exercise benefits greatly from being in a fasted (16-24 hr) state. You're light, quick and your body is devoting zero blood flow (and other resources) to digestion.

I'd say it depends greatly on the effort and the individual. Long, slow distance for someone who is accustomed to training fasted? Fat stores will suffice as an energy source.

But add in some intensity and that's gonna be rough without much glycogen in the tank - which will be the case if you've been fasting for the past 16-24 hours.