Sure, the skilled marathon runners carb loaded and ate sugar gels at every drink station, and finished much faster, but I'd love to see them try to run 5 in a work week even with the gels and pasta meals

Note that the man who did it had never run a marathon before, was not a skilled runner, and despite eating nothing he maintained a "sugar burning" heart rate for a third of the race. Were he good at it he probably could have done sub 4 hours times

And "fat adaptation [such as by carnivore diet] opens the door to the big fuel tank"

the real demonstrated differences in carbs vs carnivore......