[XFrequentist]

Great comment, I'm curious about all this too. I'd be interested in more precise data than my own vague n = 1 impressions!

I actually spent a fair bit of time delivering VO2 max tests to athletes (in a previous life as an exercise physiology lab volunteer).

This comment has me wondering if I still know any active researchers in this area, looking for ideas...

[bitexploder]

I have tried it too. I did not PR in the 5k I tried it for. I think on long runs I never noticed, but 50 minute sessions with 5k pace intervals never felt the same zip as I did on carbs. I was consistent with it for 3-4 months so I am sure I was fat adapted. I noticed my water weight was less unstable (my weight didn't fluctuate as much day to day.) I still like periods of low carb, but I found it onnerous to stay I'm that 20g or less range always. Especially with kids and a wife not on the same diet. So I am optimistically on board the low carb diet scheme, it was fine for me. I cautiously think fine for almost everyone. But... :)