[hourislate]

I have fasted 100 lbs away over the last 2 years. I adhere to an 18/6 time delay eating schedule but have done 2-3 day fasts with 1 refeed meal for a month at a time. I've also done countless 5-7 day fasts. I've gone as long as 12 days with nothing but water. There were many months where I could count the number of times I ate on one hand. My last go was every other day with just one meal on my eating days. I did that this year for all of January to the end of March and would never recommend alternate day fasting to anyone. You will mess your self and your metabolism up. You will lose a lot of muscle. Alternate day fasting should be avoided.

Never over two years did I feel any of the mental clarity or more energy you speak of. I follow guys like Cole (snake diet) and even he speaks of the feeling of dying and lying in bed shivering on a 5-7 day.

Are you sure about the metal clarity and energy levels, because I and the folks I know who fast don't seem to have those affects.

[me_me_me]

> I've gone as long as 12 days with nothing but water.

This is dangerous and please don't encourage others to do only water fast. Pure water fast is dangerous beyond 4 days or so.

You need to supplement minerals while on per-longed fast. Salt, magnesium and potassium are vital to regulatory processes in your body.

When your body uses up all reserves it will not be able to sustain those processes. It is serious business so please read up on the subject while trying anything longer than 3 days.

> feeling of dying and lying in bed shivering on a 5-7 day.

This is body telling you something is wrong, ignoring is outright stupid. Like ignoring that you are bleeding.

> I have fasted 100 lbs away Congratulations

[hanche]

I remember reading about someone who fasted for an entire year. Of course he was morbidly obese when he started, he took supplements, and he was under strict medical supervision for the duration of the fast. (Sorry, don't remember the source.)

[guerby]

https://en.wikipedia.org/wiki/Angus_Barbieri%27s_fast

"Starting in June 1965, Scottish man Angus Barbieri (1939 – 7 September 1990) fasted for 382 days. He lived on tea, coffee, soda water and vitamins, living at home in Tayport, Scotland, and frequently visiting Maryfield Hospital for medical evaluation. He lost 276 pounds (125 kg) and set a record for the length of a fast."

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2495396

[mrfusion]

I’ve yet to find a form of potassium that doesn’t upset my stomach when fasting. I’ve tried nu-salt, potassium citrate, and cream of tarter so far.

I’m about to give up on total fasts and have bone broth a few times a day for the minerals.

[beagle3]

potassium iodide might work for you.

[mrfusion]

Thanks. I’ll try it out.

[roystonvassey]

Interesting. Any studies that validate the first point? I recall research talking about how there’s little muscle wastage until day 21 in normal healthy adults.

Keen to know if we have learned more in this space

[PoachedSausage]

The figure I have seen is that muscle wasting drops to less than 0.2 kg per day once the body fully enter ketosis. Obviously, anyone considering a fast longer than a few days should do so under the supervision of a doctor who can monitor electrolyte levels etc. They can also check for the rare enzyme defect called Medium-chain acyl-CoA dehydrogenase deficiency, those with it are unable to fast safely.

[s1artibartfast]

Isn't 0.2 kg per day is a huge amount of muscle?? Thats half a pound a day!

[intotheabyss]

I know this is true just anecdotally. I'm totally ripped after a 7 day fast with none of my muscle wasting away, just the fat.

[me_me_me]

for salt look up topics around:

https://medlineplus.gov/ency/article/000394.htm

Magnesium and potasium main but not only function is to regulate heart beat. Lack of them might lead to arrhythmia and other complications.

Not sure about muscle loss.

[hourislate]

I agree, a 12 day fast is dangerous and unnecessary. I was experimenting and would never do it again. Anything longer than a 3 day fast (72 hours) is not necessary.

[me_me_me]

I didn't say that exactly.

If you supplement minerals and listen to you body response, then you can fast as long as you have fat stores in your body.

Its only dangerous if you don't know what you are doing or ignoring signals from your body. Lightheadedness is common thing people report or /r/fasting/ and almost always they don't take salt while fasting.

But I am not an expert, it feels like I have done more reading about fasting then actual fasting. So don't take advice from strangers (especially /r/fasting or worse dryfasting nutcases).

[ip26]

We need different words, really. You're describing a starvation or calorie reduction fast. More common, and what I practice, is more like a time-shift fast. For example, I exercise in the morning before eating breakfast. This is a fasted state. It trains your body to use fat as fuel. The eventual result of doing this is greater stability in your mood & mind. Your body doesn't crave carbs so much anymore, and you feel good whether or not you've eaten recently.

Your brain runs on carbs. The easiest source of carbs is carb rich food. This is why hangry people seem to want nothing but cookies & candy IMO. But your body can only hold a limited amount of free carbs at any time. Meanwhile, your liver can convert fat to carbs to feed your brain, and your body can hold a virtually unlimited amount of fat. This pathway is more difficult, so you have to train your body to use it.

So I don't think it makes you smarter or more energetic. But it does make you more stable & help avoid the crash.

[kamikaz1k]

Not OP, but I agree with you that we need different words. Because what OP is doing is not starvation (till their body is actually wasting away). Having done a few 3 days fasts myself, I can attest to feeling a euphoric energy around day 2 where I felt lighter, and sharper. I have been told it isn't universal, but from the content I have been consuming it has something to do with brain switching to consuming ketones.

Which actually brings me to another point; the brain does not run exclusively on carbs (glucose) - it absolutely has the ability to (and does) functions well on ketones. This is why ketogenic diets can work for many people.

But yes, there's lots of bio-chemical mechanisms that get kicked off when you're fasting for an extended period, so it could be something else that's unique to the people who experience the euphoria.

I am not sure if you've come across this concept, but "Metabolic Flexibility" seems to be trying to explain some of the "after burner" affects of switching around my dieting habits. Where I am no longer exercising strict caloric restrictions, or fasting on a regimen, but I am still observing some of the benefits of when I switched over. (Less bloating, more energetic even after a large meal, less voracious appetite on normal days).

[me_me_me]

Not eating for few days - is not (yet) starvation, its not 'body wasting away'.

Its a state where your body and mind need to be the sharpest in order to catch food. Or else due to lack of fuel you will enter actual starvation (no fat reserves).

When you have reduced calories intake ~~500kcal a day you are signaling to your body that you can find/catch food but there is not a lot of it. Your metabolism will slow down in order to adjust to reduce calories. You loose muscle mass much faster than when not eating at all.

I have done multiple >3 days fasts and I havent experienced this sharpness feeling though. It seems some people do and some don't.

Also worth mentioning keto is natural diet of Eskimo people, they survived generations eating seal's meat and fat. So keto is not some crazy nutjob diet invention of 21st cent.

[snarf21]

My understanding (and experience) is that this clarity is usually just about the lack of all the crap that normally makes you feel awful. Things like sugar, dairy, and processed grains plus preprocessed foods. I've always found that after 10 days, you start to feel amazing and do so for around two weeks more before your body starts to adjust.

[plutonic]

The mental clarity comes from adrenaline. When you fast your body slowly uses up its glycogen store and releases adrenaline to compensate. Presumably it does so in order to keep you active / motivated enough to go look for food to refill your glycogen stores. It is this adrenaline that gives you the mental clarity and causes you to have trouble sleeping when on a fast: fasting is essentially natural adderall.

On top of this, once you use up all your glycogen, your body enters a period of autophagy which causes disfunctioning cells and protein fragments to become broken down and reused. This causes your body to function more efficiently, including your brain.

[king_panic]

That's true but it's also true that neurogenesis will start at some point during a fast. For me, it's around day 3 or 4. It's an evolutionary mechanism to form new connections in the brain to help find food/survive.

[sambeau]

When I fasted I remember the feeling of energy kicking in around day 2-3. I had moments of supreme clarity but also moments of fuzziness. The energy boost was real though. I continued to exercise quite heavily so didn't't see any muscle loss. I'm quite a big guy so there were a lot of fat reserves to melt—my skin became very greasy as if I'd eaten a very fat-heavy meal, I could even taste the oil in my mouth.

I wonder if, if you are not a big eater, then the difference might be less than if you tended to be full of food, digesting away all day and night. Similarly, if there's not a lot of fat on you maybe, rather than burning fat with an energy boost, you end up burning muscle and feel tired?

[nwienert]

I’ve never done the long term fasts, but my anecdotal experience also confirms this - I definitely have significantly less mental clarity on any type of fast I’ve done, to the point where it definitely affects my productivity even by end of day 1.

[dasudasu]

Myself as well. You just hit low blood sugar. Technically not fasting, but I have an appetite so weak I can skip meals easily and will do so if I don’t pay attention. Eventually I just feel very lethargic and enter what I can only conceive of as “starvation” or “energy conservation” mode. It’s not pleasant. I also have trouble with muscular mass being the first thing to go.

[Delk]

I'm pretty much that way, too.

I think I also just become more irritable if it's been too long since the last time I ate. It definitely doesn't seem to improve mental acuity for me, and any kind of physical activity is just going to feel worse. I've never tried any kind of a formal fast, though, so I don't know if there's something to planned schedules that makes it different.

I can kind of see how I might, under some circumstances, enter some kind of a state of quicker thinking after fasting, but I think it would be something similar to sleep deprivation, where you get perhaps a bit "hyper". That's not really a state I necessarily strive for either.

I've also never been overweight, and have always had more trouble gaining weight than getting rid of it. I wonder if that has something to do with it. I suppose the metabolism might be different if you've got some fat stores vs. if you're rather low-fat.

I can understand how fasting could e.g. have differential effects on cancer cells and thus be useful in specific circumstances. I also understand that people have rather different reactions, so I don't doubt that some people achieve some kind of a state that feels good or useful by fasting. But I don't really understand the hype, or calling it a panacea.

[jjallen]

I start to get this clarity and energy around the 24 hour mark. It is unmistakable.

Each time I hit that point I get the clarity and energy, and remember that it happens each time. Pretty interesting. So much energy I can't sleep and end up eating when I can't sleep which breaks the fast.

I am only 5kgs over weight at this point if that is relevant for anyone.

[thisisbrians]

Many, many people who follow fasting/ketogenic diets report heightened energy and focus, myself included. This usually comes after the carb/keto flu phase once adjusted to the low carb intake and after the body has gone fully into ketosis. You have to be careful to get enough salt while fasting or eating very low-carb, though, as your body can struggle to hold on to water without those carbs you're used to eating. Consuming too little salt can definitely contribute to feeling sluggish.

[king_panic]

You don't follow Cole if you don't know the difference between the effects of dry fasting and wet fasting after 5-7 days. If you do know that, you are purposely making a misleading statement to support your argument.

[astura]

Same here - I've been eating only one meal a day mon-fri for literally years. I also do 2-3 day fasts here and there, my longest was five days. No changes in mental clarity and energy.