Is this a hippie variation on the spornosexual trend ?
Not the way I see it. I'm a brain cancer survivior that has done some fasting and running. I've fasted for 72 hours twice in the last year and a half. The fasting reasoning is based on evidence of studies out of the University of California. There's empirical evidence showing that severe caloric restriction "reboots" a person's immune system. My immune sytem let me down by allowing some out of control cells to grow in my head, so I've "rebooted" it twice. Maybe it'll help in the long run. In the short term, I've become much better acquainted with my actual caloric needs. Those needs are much less than I thought. Not only that, I ran two miles after fasting for nearly 70 hours. I was pretty fast and felt great. How many folks can lay claim to that? Potential of cancer regrowth aside, I can't really say I've felt a whole lot healthier ever before.
Sorry I didn't want to undermine your exploit. I was one of the first to share this story, because it is so impressive. And I'm fascinated by the Running hunter theory. But I followed a link to another post on your blog, with a picture of you, and you looked lean, with a six pack .. So my mind automatically linked to the recent spornosexual post.
Fasting is one of those subjects that never ends. Good thing you're saving so much time cooking and eating and pooping, because there's a lot of reading to do. I found another story of an endurance event in ketosis. That led me to a Ketosis 101 article, which mentioned the longest supervised fast ever undertaken. Can you guess how long it was? Here's a hint: the subject lost 276 pounds. You know the journal article will be good when it has a reference to the Guinness Book of Records.
This is fascinating. I always thought of ketosis as a kind of breakdown status, when the body starts to "eat itself" after running out of fuel. And I have felt miserable the few times I hit the wall, wasted and lethargic, with the weird taste of metal in my mouth. It never occurred to me that ketosis could be a long term option for functional nutrition, though I see it is an intended component of Atkins-style low-carb diets. The endurance running hypothesis is intuitively appealing, and Xavi makes a good point that persistence hunters would not likely have vast stores of glucose-rich foods like the high-octane gels and sugary sports drinks that fuel a modern marathoner. 50K in 7:45 is not an especially brisk pace, about 15 min/mile, but even walking that far after three days of fasting would have seemed unthinkable to me. And of course he does much of it barefoot.