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By no means this post should be treated as medical advice. Nothing here has been done under medical supervision. It’s just a personal experiment.



I recently ran an ultra after almost 4 days of fasting. I wrote about the experience here: Made it! 50k in complete starvation. The current post is its continuation.



In the last months I’ve built up a serious opinions about what its right and wrong about our current diets and a lot of it has to do with human evolution and running.

The endurance running hypothesis

“The endurance running hypothesis is the hypothesis that the evolution of certain human characteristics can be explained as adaptations to long distance running. The hypothesis suggests that endurance running played an important role for early hominids in obtaining food. Researchers have proposed that endurance running began as an adaptation for scavenging and later for persistence hunting.”

Daniel E. Lieberman proposed this hypothesis on a 2004′s paper and Books like Born To Run or Why we Run support the same idea. If this was the case, it would mean that we use to hunt by chasing antelopes for hours until the animal collapses from overheating.

The exposed arguments make a lot of sense in my limited knowledge, but they fail to explain how these hominids could have enough energy to sustain these ultra-runs.

In the same wikipedia article it says:

Such a long hunt requires high amounts of dietary sources of water, salt, and glycogen.

To build up glycogen stores endurance athletes do the “Carbo load”, that means eating generous quantities of carbohydrates in the hours prior the workout. If running, this load will last about 2h or 24km before this person “hits the wall”. That means, running out of energy and collapsing (I’ve hit the wall few times in the past). That’s why they use energy bars and gels, to refill these storages and keep going.

That will be a beautiful theory if it wasn’t because the type of food necessary to build up this storage was pretty much nonexistent or at least not accessible. Just google “carbo loading foods”. And they were hunting because didn’t have food in the first place…

The only way to explain it if they were in an state of ketosis.

Research

There is research going on in the field of ketosis and endurance sports. Peter Attia was the first reference I found on Ketosis, through a Tim Ferris tweet long ago, and I’ve been following him since.

Recently, also through Tim Ferris I discovered Dominic P. D'Agostino who also has a lot of publications that I still have to go through.

There are lots of other sites under the Paleo flag too, and some experiments with Ketosis and long distance running.

I couldn’t find any publication about ultra distances and significant amount of fasting. This, the success in other fasting experiments I’ve done, and the inability to to comprehend the mentioned hypothesis engaged me to do the experiment.

Competition

By no means I’m a professional athlete. I’ve been in 3 races in my whole life. Its not my goal to be fast when I run, but I enjoy the pressure and preparation that comes with a race. I follow this world quite closely.

Since my last meal until I started running I lost about 4kg. I did not burn that much fat. My last poop was 48h after the meal. Since then until I started running my weight just decreased 0.5kg. That means I had about 3Kg of food in my guts…

Using glycogen instead of fat its more efficient. It uses less oxygen to do the conversion into energy, but If you’re body weights 3kg less, that’s a lot of energy savings in a long distance race…

People get crazy buying shoes that can save them few grams. Well, how about saving few Kg? Plus you don’t have to bring any gels. And you won’t have any gut problems, and that includes not having to take a shit during the race.

That sounds like a pretty good deal to me.

Conclusions

I don’t know how much of what I accomplished its due to a process of adaptation (for the last months I’ve been eating once a day) and how much is something that we have built in our systems and we can just trigger with the right circumstances.

All my arguing may sound over simplistic, and probably it is. I’ve been following the research on this field for a while and I can barely understand any of the technicalities they talk about.

The key point for me its that IT IS POSSIBLE. And probably way beyond of what I did. I’m not a nutritionist, nor an athlete, and it wasn’t even that hard. My reasoning was simplistic, based on fundamental questions that transcend the details.

What’s next

I’m suspicious that there are big differences between nutritional ketosis (induced by reducing the intake of high glycemic index foods) and ketosis induced from fasting. In other runs done in nutritional ketosis I didn’t feel that energetic (but it’s hard to compare since I’ve never done it that far in distance). That’s something I may explore.

I think few days of fasting offer unique areas of explorations. Right now there are a couple of things I’m curious about.

Since there is no input nor output of food, and I can control my hydration very easily I should be able to get an idea of my fat burning rate.

The other thing its related to electrolytes. There is a lot of theories out there that relates the lack of electrolytes and cramping. By taking food out of the equation I will be able to control my minerals intake and I should be able to get some straight forward answers.

And of course, (with extra training) I’ll try to see how much far I can go with nothing but my legs and water.

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