[jordanmoconnor]

Someone on Twitter calculated about 55,000 calories burned. Not sure if he had things to consume while running - but 8 - 10 lbs of fat burned in one day is wild to think about.

[cfj]

That seems way too high. A rough ballpark of energy expenditure while running is 1000 kcal per hour. Strava has the activity at 16,751 kcal.

[darkwizard42]

Dang, that would be SO impressive... <1000 calories an hour would mean he is running SUPER efficiently from a body perspective, but of course, with the right hydration, nutrition, and temperature it is all possible to burn less calories.

[WastingMyTime89]

Definitely had things to consume. I don’t think you could go through this kind of effort on your energy storage only. I don’t think it can be mobilised that fast. Hydratation probably is a major concern too.

[mikestew]

Not sure if he had things to consume while running

Oh, he had things to consume. I ran 16 miles on hilly terrain on Saturday, and just for that I brought about 500 calories with me (not all consumed, some was "just in case").

It has been said that your liver stores about 2000 calories of glycogen. Divide by ~100 calories/mile, and now you know why marathoners hit "the wall" at about 20 miles if they don't chomp on some calories along the way.

[xhrpost]

IIRC, a gallon of gasoline is about 37,000 calories. So that's a lot of energy he utilized, all through his body burning fat and carbs!