My understanding, barring real genetic outliers, is that the human body just can't go as fast in a fat adapted state. I would say "any runner". Meaning anyone w

My understanding, barring real genetic outliers, is that the human body just can't go as fast in a fat adapted state. I would say "any runner". Meaning anyone with a few months of real training under their belt is going to run sub marathon efforts slower. The article you linked pointed that out. This isn't just for elites, but everyone. Most recreational/non-professional runners run sub marathon races. This implies some important things about how you train and eat. 1.) When doing max effort running, to push your body to it's limit you need some carbs. 2.) To run your fastest race you need some carbs. You can still train and do well without them, of course. I think for most runners it's fine and the difference doesn't amount to much in practical sense.