[dlkmp]

It doesn't. That's why "Hungerast", i.e. sudden loose of energy due to all carbohydrates being used up is a thing in all endurance focused sports.

[jniedrauer]

It's actually not a thing in "all" endurance sports. Once you push into the realm of ultra endurance, athlete become so efficient at fat metabolism that they never "hit the wall" so to speak.