This is DEFINITELY not a great idea without pre-clearance from a doctor, and even then it's not great for you. I would imagine this places undue stress on many body systems. Your muscles (and brain!) really really want glucose when you're working this hard. AND he was at altitude.

Ketosis workouts DO work very well though. I just don't recommend an Ultra while fasting...

Your point is valid, but your wording could have been better (I assume that is the reason for the down votes).

He doesn't mention consulting a doctor to explain the health risks before undertaking this. In my opinion, even if you think a medical professional is going to say you are stupid for trying it, you should still consult a medical professional. You need to be aware of the risks and their signs, and when you post something like this on your blog, it should be prefaced with you probably shouldn't try this.

What if someone dies trying to recreate his experiment? (I know common sense etc...)

The only fundamental difference between this and a 'proper' scientific experiment is the p value. All scientific experiments have cavets, and all have a probability their finding could be erroneous. Of course, no one should write a textbook based on this one guys self-reported experience. But, assuming he is accurately reporting it, it is evidence that this is _possible_ which is a very important thing to discover.

Yes, it may only be possible in 0.01% of the population, that is the type of thing which a larger-scale study can evaluate, but whatever they find, it will be an interesting result which would have been less likely if he hadn't shown it could be done.

A proper medical study also has doctors monitoring for any risks. They would run blood work and check for anything wrong - it's hard for one person to draw conclusions about how healthy this is if he wasn't baselining and monitoring different vital statistics (liver enzymes, etc.)

Also, everyone's body is different: he may just be a genetic freak who is able to do this. Especially with heath/body claims, be very wary that one person's results will be able to transfer to anyone else.

Nonsense. A proper scientific experiment would have controls and independent results and medical oversight and calibrated measurement equipment and a clear definition of what's attempting to be proved.

This is a guy fooling around and blogging for attention. Dangerously so. p=1, no scientific method = anecdata. His conclusions? Pseudoscience. It's dangerous to him personally and it's damaging to society broadly to promote such without caveats. So I'm providing them.

He has gathered more data than had he not done it, or not blogged about it. You're right that it doesn't meet any scientific criteria for 'fact' yet, but it is data of a sort, and may be a helpful step on the road to the furtherance of science.

Wow. I didn't realize "doing random stuff while taking no measurements, and then later writing about it" qualified as "the furtherance of science." A sample size of 1, combined with an attitude of ignorance and machismo, helps explain why "medical remedies" like bleeding people with leeches and giving them liquid mercury to drink endured for hundreds of years despite no actual evidence that they worked or were safe.

Reality check: nutritional deficits lead to cognitive deficits. The Atkins diet is known to lead to heart disease, which Atkins himself died from.