I ran my last marathon on keto and it was fantastic. Five stars, would recommend to anyone. There was just no slowing down and I didn't even notice the wall around the 20 mile mark. Where glycogen is finally burned out.

I didn't find it sustainable as a lifestyle though because I eat in other peoples homes a lot. And it's just rude to not eat what they put in front of you. Eating out was just strange as well since I would just eat the protein and leave the sides. Or ask to substitute whatever it was with salad.