I did not see a doctor. Not before, not after. The truth is that even if I had seen one I wouldn't take in account her opinion anyway.

The current standards for nutrition are based on a diet rich in carbohydrates. Any response from a doctor (at least the ones I have access to) will discourage this event. It just doesn't fit on their models. Plus they have to play safe. I appreciate all the people who are concern about my health. I'm doing fantastically well. Thanks.

I do believe that ketosis is the "default" state for the human being. I have plenty of reasons for that and I'll try to explore more arguments in other posts. Its a very broad subject and I wanted to narrow the scope.

I didn't do this experiment out of nowhere. I've been running in ketosis for long time and I know myself pretty well. I've been reading and educating on the subject. I'm not completely stupid. I know the risks and I know there is a lot we don't know about. But if I've done it its because previous runs and experiments gave me the enough confidence.

This post doesn't suppose to be a scientific study, not to give any medical advice (I'm taking note from your comments and I'll add a warning). Its just my experience based on what I thing should be a more commmon approach, to focus more on the fundamentals than on a micro view.

  See Micheal Mosley's Eat, Fast and Live Longer

I applaud the author's spirit of mad science and adventure.

As someone with a lot of doctor friends and family, I think it is pretty clear most doctors are not familiar with the relevant research and by default give a cautionary response which merely parrots back the status quo fears, but they're even more risk averse due to malpractice concerns. In terms of getting your blood work done, sure, I'll agree that seems interesting.

My father, a doctor, used to be afraid of low carb/ketosis diets, because "bacon, cheese". Years later he read the relevant information and completely switched camps.

Finally, self experimentation can be dangerous, sure. But that doesn't mean it isn't valuable and interesting. Do you think people should never do potentially dangerous things in pursuit of adventure, knowledge, truth?

A couple points:

* He ran 50 KM in 7 hours and 45 minutes, which amounts to fast walking. In real terms, he probably ran some but probably walked most of it.

* If you're going to do something like this, please do it under the supervision of a medical doctor. A 50km isn't a big deal, virtually anyone who can run a marathon can run a 50k, but people do die during this events. Respect the distance.

Edit: Here is his Strava entry for the event: https://www.strava.com/activities/morning-run-436423654?utm_...

From my sloppy napkin math, it looks like he ran the distance (slowly) and probably stopped a lot and had his device configured to pause the time when he stopped.

I don't mean to sound down on the guy, he got out there and did 50km. And he specifically mentions he's no athlete. I am glad he documented his experience. But please don't use this as part of any "Couch to 50K" kind of scheme. Ketosis doesn't work like creatine.

Edit 2: A metric/imperial conversion pace chart here: https://www.globe-runners.com/sites/default/program_builder_...

Edit 3: pneumatics' comment, below corrects me: "The time spent moving was 5:49. His pace, excluding the time stopped, was 11:12 min/mi.

With the elevation gain, this is most definitely running." This is a pretty good performance for a newbie, IMHO.

For those saying it's slow, you've either never ran an ultra on rough terrain, or you've been on the cover of running magazines.

The whole blog feels like a confused agenda masquerading as hand-wavey pseudo-science. Do not like.

Ketosis is really quite well studied at this point, I don't really think this adds anything to the mix. Also why conflate fasting and ketogenics?

Congrats on not dying I guess. As someone who has been around elite athletes my whole life an article like this doesn't phase me at all. A bad diet can throw the best athlete off her game. On the other hand, Michael Jordan can win the NBA finals on nothing but water and flu in his stomach. There are a lot of factors on what it takes to get through a 50K. I think a lot of us runners could do it starving ourselves, but we'd just feel very bad the whole race.

My experience in endurance sports is with cycling, and I have a friend that used a "ketosis" diet to help lose some weight. My understanding of the fat burning process is that it can only happen so fast, so with fat as your fuel source you are only able to support moderate intensity levels. This could explain the 7h 45 min minute time for his 50km run (~31 miles).

I know if I am riding at race pace for a couple of hours and don't give myself fuel then I am in trouble, but riding at lower intensities I can go for a much longer time without eating as long as I have water.

I just started training for my first marathon, and am trying to do some reading on the subject. Hal Higdon's position is I guess what you might call "traditional": your muscles use glycogen as the preferred energy source. Around mile 20 is when most people deplete their glycogen and start burning fat as the primary source of energy, but this is much less efficient, resulting in a performance drop. If this is indeed true, then I guess it means that if your goal is top performance, then carbs are your friend. If your goal is fat loss, then low-carb diet plus long endurance exercise is for you. Does that seem right?

For a community of 'hackers' (which I assume should embrace trying out new things and questioning traditional values), the majority of these comments sound very negative and not constructive.

He did it in 7:45. They don't stop the race timer because you stopped.

That's towards the back of the pack for a trail 50K with that kind of elevation profile.

It'd be better as an experiment if we measured the author's VO2Max, his 1 mile run time on a track, and then ran the 50K on a track. Measure ketone levels, etc.

I've seen people die running a half marathon. Please don't push your body to the breaking point just for giggles. Work your way up.

While this may be possible, I would worry about the effects on your liver. Ketosis does put additional strain on the liver, and while it doesn't seem like the side effects of extended ketosis are dangerous, there simply aren't any studies on ultra-endurance exercise during ketosis. And while studies on extended exercise during ketosis would be a good thing, they should be performed by researchers and doctors who know what the risks are and can monitor them appropriately.

IMO this is dangerous. Just because our hunter-gatherer ancestors did it doesn't mean it's healthy for us. For all we know, this type of activity could wreck your liver and contribute to dying in your 30s (our ancestors did not have a long life expectancy). So even if it was a survival adaptation, it may have ensured the survival of the herd at the cost of the individual.

I've played with ketosis. You can verify your body is in a state of ketosis using "keto sticks" that you pee on. They change color and prove that your body is outputting ketones. That's also what causes your breath to smell like something died (my wife's comment).

One of the leading thinkers on this is Tim Noakes who has written some excellent literature on the subject and is a keen runner. He became famous for "Lore of Running" which is a tome of a book but is an excellent primer for any runner serious about nutrition and metabolic processes.

Noakes has more recently joined the low carb/low GI movement and has some pretty radical thinking in the area.

I would also echo some other commenters here that Ketosis is IMHO not a healthy state and can have quite far reaching health consequences. One of the by products of ketosis is acetone which is what makes your breath smell - so there are some fairly radical changes in your body's chemical functioning as it goes into starvation and survival mode.

I tend to gravitate away from radical experiments like this and more towards what the leading edge professional athletes are doing, minus the steroids. They have plenty of motivation to innovate in the field in a sustainable way.

Certainly an interesting experiment.

As somebody who only engages in "moderate" endurance activities (bicycle rides ~100 miles) I can relate the difference diet makes for me on long activities.

Endurance athletes speak of a thing called the "bonk"[0] - a point beyond which continued activity becomes much more difficult. This state is due to the exhaustion of glycogen stores in the body.

I've encountered this only a few times, but it's a really interesting phenomenon. In times I do not prepare well enough, I just run out of "energy." Everything gets harder, and I don't recover from it. It's not the case that I cannot continue, but continued exertion feels much more difficult. I feel mental fatigue as well, and I have felt "light headed" in this state.

This is why it is recommended to consume carbohydrates when engaging in endurance activities. It's not that you can't continue on ketosis, it's that you continue in a very suboptimal manner, and in something like cycling (where you are moving quite quickly) a sensation of light-headedness can be exceptionally dangerous.

Incidentally, the rate of depletion of glycogen stores is relative to the intensity of the activity. Operating further below the aerobic threshold will allow one to deplete the glycogen stores more slowly. If the OP is in good shape, this probably played a role in his success, as he might be running at a less intense pace than he would be capable of were he consuming carbohydrates.

[0] https://en.wikipedia.org/wiki/Hitting_the_wall

Hacking your own body can lead to health issues obviously. But...

This may be the way everybody runs in the future.

A bit like Cliff Young[1], a potato farmer that won the Sydney-Melbourne ultra-marathon.

[1] https://en.wikipedia.org/wiki/Cliff_Young_(athlete)

Could all the people without medical knowledge please stop saying that their lack-of-medical-knowledge make them smarter than the guy that actually did this? Your requests for various random chemical levels are stupid. We have done science for thousands of years before blood tests were invented.

I'd like to add my own data points for low-carb/ketosis and exercise. In the beginning it was very hard and I felt extremely lethargic (typically 3 to 4 days after switching to < 30g carbs a day). My exercise at the time was 2 miles on the treadmill and 20 minutes of full body weight lifting (squats, etc).

The worse I ever felt was during that time (3-4 days in). After that I would slowly improve and within a few weeks could almost reach my normal max, though never exceeded them. The bonus part was that I was melting off pounds of fat.

This was just my experience. I found that salty drinks (such as chicken stock) helped a lot when first beginning low carb to prevent the lethargic feeling ~3 days in.

Ketosis sounds nice and all but it makes ones breath stink bad. I think id rather be fat.

Not something I would try, or would have tried at what I suppose is his age. I will say a runner in training can get into ketosis with no need for fasting--visiting the downwind side of marathon finish chutes would probably convince you of this.

I did "hit the wall" a couple of times, but my diet leading up to the race was no different from that before other races. In one case it was inadequate training. In a couple of others it was setting out at too fast a pace. Now, that is not to say that I felt good in the others--I felt awful but bearably awful.

I think the most important factor should not be whether you can do it or not, but if you can perform better in ketosis than those who are not in ketosis.

I know the 4 months I went on low/no carbs, I had never felt better, had more energy, or lost weight faster. I lost 43lbs, saw my cholesterol and triglycerides go from marginal to perfect, and ate as much as I wanted.

Course then my gallbladder stopped pumping and I haven't tried it again, although I don't see why I couldn't.

I once tried just 16 miles after just 36 hours of fasting. It was interesting. I don't remember a whole lot, other than that it was a serene kind of experience. I was in quite a different mental state from the run-of-the mill run.

Funny that this gets upvoted so high and a more reasonable article that was posted in the same day (https://news.ycombinator.com/item?id=10931349) did not.

I've done ketosis, high carb, and moderate carb, and the fact is that while ketosis can work for some, it can be damaging to others. I tried keto for a while and it raised my fasting blood glucose levels to pre-diabetic levels. As soon as I went back to a moderate carb intake, my blood glucose was back to near-ideal. Obviously you should take further tests (HbA1C) to be absolutely sure if you're at risk, but it's not all smiles and rainbows for keto, you really need to make sure your body can actually adapt properly to the changes that are going on in your body as a result of the diet that promotes keto.

Related: https://news.ycombinator.com/item?id=10919375

«And they were hunting because didn’t have food in the first place…»

I laughed at this one.

This is a gnarly run. Almost 7000 ft of climbing (he gives the value in m, but all my reference points are in feet). It appears he was not auto-pausing, but did stop quite a bit. The time spent moving was 5:49. His pace, excluding the time stopped, was 11:12 min/mi. With the elevation gain, this is most definitely running.

I did ran all the way. Surely it wasn't fast, but take in account that there was 2000+ meters of elevation gain.

Running means you are jumping through the air, so that at most one foot is in contact with the ground at any time. This can be done without moving forward, so there is no lower bound which separates running from walking. Walking means that at least one foot is in contact with the ground at all times, and there are at least brief periods of double support (two feet down).

I can walk up to an 8:30 mile pace. Elite race walkers can outwalk recreational runners; the paces are around 6:00 at that level, which is astonishing (though not in comparison with elite running of course).

If someone covered some distance at 11:00 to the mile, we have no idea whether they ran or walked without eye witness or video evidence of what it is their legs were doing.

I definitely ran my first marathon in 2003, in some 5:05:12. That's like 11:44 to the mile or thereabouts. I definitely made a point of not taking any walking steps in this thing. It happened by accident several times, but I immediately went back and re-ran those small stretches of the course where I had strayed from the pure running discipline. On subsequent ones, I didn't make a point of that at all, just the first one. I've never taken planned walking breaks or walked extensively, but I never re-ran any walked steps. The clock is ticking; no time for foolery! :)

Strava shows the spent moving time by default. If you want the overall time to be shown you have to tag it as a "Race". https://strava.zendesk.com/entries/22428904-Using-Strava-Run...

I also want to point out that when running barefoot/minimal you reduce the stride and increase the cadence. In my experience the result of it is that speed its generally reduced, specially downhill and flat surface.

And by going completely barefoot the surface of the terrain it really defines the speed you can go. When going fast the pressure on the sole its greater and if the terrain its harsh you are forced to slow down. A lot of time until the point of walking, or even slower. In complicated terrains the potential outcome for stepping over the wrong stone it really makes you to be conscious about every movement, slowing down as well.

50K isn't easy for even people in good physical shape, especially if there are hills!

I was watching my fiance run and someone died literally right in front of me at the Brooklyn half-marathon in the fall (he was a young guy - I'd say late 20s). He collapsed right at the finish line and they couldn't revive him. The crazy thing is there was no mention of it after the race or anywhere, I tried googling to find out more info. but nothing. The only info. I found was on /r/running people where people who were also in attendance were talking about it. Marathons just seem so unnatural to me.

> I've seen people die running a half marathon.

From the "Those who don't learn History are doomed to repeat it" department: the whole reason people "run a Marathon" is because of the legend of a Soldier, Pheidippides, running from Marathon to Athens and dying after announcing victory in battle.

If people are aware of this basic information and still are stupid enough to run without any preparation, I'd say they would be candidates for the Darwin Awards.

Actually seen firsthand, or read about it having happened? (These are very different, because they imply much different prevalence.)

The author of the article records a short clip describing how he's feeling at each waypoint, and doesn't seem to have pushed himself terribly hard.

I think you have to think about how those people died. Heat exhaustion? An underlying heart condition? I don't think they died of not having enough nutrients, or not eating soon enough before running.

So, I played with ketosis and lost. 7 years ago I weighed 260lbs, having converted a once fit and muscular physique into lard with the help of my desk and startup. I decided to do something about this, and to simultaneously run an experiment to determine my general metabolic rate and baseline nutritional requirements.

To do this, I stuck myself on a fixed daily 700kcal diet, ran 15km a day, and got on with life as usual. I measured blood sugar, weight, fat mass, resting pulse, b.p.

Needless to say, I lost weight, fast, and was down to 180 by the time I ended the experiment, four months later. 80% of the mass I lost was fat, 20% muscle, my sleep apnoea was cured, and I felt good about myself for the first time in years.

I also got some beautiful graphs out of it. By keeping the inputs all constant, I could see my weight shifting along a curve as my metabolic requirements shrank as I dropped mass, I could see blood pressure and glucose moving in curves beautifully correlated with my fat mass. To that end, everything went as planned.

About six months after this, I started being sick. I'd spend days puking and delirious, and would then be fine for months, or weeks - came and went at random. Several years of baffled doctors later, I diagnosed myself with gall stones, got an ultrasound, confirmed my hypothesis, and had my gall bladder removed last year. Turns out that having a prolonged low calorie diet pissed my duodenum and gall bladder off mightily, and they grew a huge cluster of stones in short order. I'm seemingly fine now, after five years of misery.

Long story short, you're not actually invincible, don't learn this the hard way like I did.

>I would also echo some other commenters here that Ketosis is IMHO not a healthy state and can have quite far reaching health consequences.

Are you a doctor? Are you qualified in any way to be giving health recommendations?

No? Parroting the crowd doesn't help people. Especially people with insulin sensitivities that could absolutely be helped by a low carbohydrate diet.[0]

0: [pdf link] http://download.springer.com/static/pdf/335/art%253A10.1186%...

> so there are some fairly radical changes in your body's chemical functioning as it goes into starvation and survival mode.

Ketosis is not a "starvation mode", it's just one of the normal ways your body provides energy. During most of human history people didn't have plenty of carbs available all day long, so ketosis was most likely the normal state and not an exception.

"Starvation mode" because of eating less is generally just a myth and an excuse for people why their diet failed.