Fasting - all types (intermittent, long, dry, etc)

[stadtaffe]

Is it more the amount, or the type of food to refeed with? I feel like a hunter/gatherer finally getting a deer after a week of hunting wouldn't eat himself to death on a refeed.

I think it has to do with the speed. From what I read, it says that once the body realises it is being starved, it switches off the digestive system, production of enzymes etc to save energy.

It will not just switch back on again in an instant like a light. It's like you need to 'tickle' it back to life over perhaps a 6 hour period. So I think my vegetable soup with beef broth and small strips of meat does that better than a steak.

Another excerpt from Tools of Titans, from which i've quoted previously:

Anecdotally, I have had big steak lunch with friends after four days (96 hours) of fasting, with no ill effects.

Okay, so after 14 days, be very careful how you start again, after 3 days just tuck in and enjoy.

I might just tuck in next time and see what happens, the worst that has happened to me is that it sits in the stomach undigested for 24 hours, just a bit uncomfortable but no sickness or death. All that stupid click-bait aimed at the most unhealthy segment of society, telling them to be careful not to carelessly die..

I will not be doing 14 days either. The other week I gave up after 5 days while trying to get to 8 days. It just seemed like a miserable endeavour to stretch it out that extra bit, diminishing returns, would have really ruined the weekend. Rather eat again for a few days then resume.

This is doing wonders for my body I want to do the final fast soon and get it out of the way before something in me cracks or gets distracted. Lose that last bit of fat.

As an update, after the first 30 days of my "fasting" experiment, I can report the following.

- 18 of those days were full day fasts
- 10 of those days I had one meal
- 2 of those days I had two meals

That is good you're keeping data on it. I am writing my morning weight daily, occasionally more than daily in a square box at the top of the diary page. Have logged most major fasting events in this thread.

Those meals were ones I couldn't politely avoid with family and friends.

This is why I can succeed at this right now when I am left to my own devices but when I am with family I've got little chance. I will find a way to stay at the same lower weight next time with family without impolitely refusing anything, can't go and undo all this hard work, but I would not be able to consistently get lighter in that situation as is happening at the moment.

The thing I learned from the recipes about the bone broth was to wash the bones first, or blanche them. So after 5 minutes of boiling I threw out the first lot of water then refilled it and let it go for hours. They say if you don't do that it turns out bad. The recipes also recommend roasting all that meat and bone before the boiling but I did no bother.

Somewhere I was reading about fasting raising cortisol and the fight and flight response which explains a few things. I always wake very early when fasting which is not such a bad thing. But this "fight and flight" thing explains behaviour around traffic. The other thing is, last night the neighbours were talking loudly in the hallway and slamming a few doors and I felt like they were personally attacking me and felt like fighting back. Same thing at the gym this morning, I was probably still in mild ketosis / low blood sugar, every noise in the change room was making me want to jump up and hit someone.

Just pleased I don't have many stints of this left and won't be doing this long term.

 

[Lawrence87]

I am thinking of doing a 3 day fast for the start of Great Lent, if I get a blessing to do so.

I've done 24 hours before, but nothing beyond that. I am a bit conscious of not over doing it. Any recommendations for doing your first 3 day fast? I am prone to getting headaches (I had one pretty bad during my last 24hr fast) I am hoping to avoid this again if possible, if anyone has any tips?

Thanks

 

[Laner]

I am thinking of doing a 3 day fast for the start of Great Lent, if I get a blessing to do so.

I've done 24 hours before, but nothing beyond that. I am a bit conscious of not over doing it. Any recommendations for doing your first 3 day fast? I am prone to getting headaches (I had one pretty bad during my last 24hr fast) I am hoping to avoid this again if possible, if anyone has any tips?

Thanks

I drank some coffee during my 24hr fasts. I assumed my headache was coming from the abrupt stopping of morning coffee rather than the lack of food.

But I do 16hr fasts every day except Sunday, and have for over a decade. So 24 hours is actually pretty easy.

 

[Uncle Cr33pin]

 

[stadtaffe]

The need for less sleep while fasting seems to be universal. It is quite uncanny, I slept 4.5 hours last night but feel relatively good and have not needed any naps or excesses of coffee this time. Rather uncanny. Fall asleep easily but don't stay asleep as long.

There is a very good 'red pilled' and detailed discussion of it here -


Although there is plenty of discussion about hormones, leptin, growth hormone etc, the clearest explanation is that it stems from a time when our ancestors needed to hunt their food. If you were running out of food and it was a do or die situation the body felt it was better that you did not sleep too much, it woke you up and ran on less sleep. More detail in some of the posts in that link.

 

[stadtaffe]

I set a new PB today, 6 days

Well technically was 6 nights, I stopped eating in the evening of Saturday 13th April at 7:30pm and resumed this Friday morning 19th April at 9:50am. On Sunday 14th April did a lot of exercise which brought me quickly into ketosis.

Dropped 2.6 kg over the time and actually can see a big difference in the mirror. I think I may only have one more of these to go to hit my target weight.
Previous PB was 5 nights, but I'm not in the same league as some guys in this thread who can go for 2 weeks It also has to do with wanting to enjoy a normal weekend. It's a cyclical diet. Suppose one could call it intermittent fasting but I prefer to call it cyclical diet. Starve during the week, do my normal tasks and work, walk a lot but avoid cardio or weights. Then refeed on Friday, and allow 24 hours for the body to recover from the fast then enjoy 2 days with a lot of cardio and weights and other normality before resuming the starve on Saturday, Sunday or Monday night.

I don't think I will post too much in the belly fat thread as it makes me sound as if I'm fat in that way which I'm not. Have very little fat left there, there's actually more in the lower back. Actually noticed in the mirror my quadricep area seemed to go down a bit in flab girth after this fast as well which I wasn't expecting. This is not only about optics, it's also to make weight for some sporting events and make it possible to run that bit faster for longer through being lighter.

Will see if it works. Was very exhausted after the refeed today, that always happens. Have stopped fearing refeeding syndrome although there were some slightly scary pains upon resuming to eat. I knew it would have been wrong to start with a steak after almost 6 days without food so I didn't. Resumed eating with alternate serves of wholemeal bread with fried egg and bacon and bread with avocado. Look forward however to getting back to meat tomorrow but did not want to start with it, nor with the whole messy process of cooking some kind of bone broth soup overnight which I did last time I fasted 5 days. May do oxtail one day though the butcher said I have to order it in advance, but it's messy and stinks out the whole apartment. It's good for you though with all that bone marrow. But more bread was consumed today than I like to consume I normally don't buy bread at all but chose it deliberately this time as part of this refeed. It's always different experiments, see how they go each time.

Someone suggested juice fasting in the other thread - I read up on it but when I heard that cell autophagy does not happen, I decided against it. Just stick with electrolyte water / snake juice, black coffee and herbal teas. Also thought it would be too much work and logistics getting quantities of vegetables in here, slicing, dealing with pulp etc.

I was very intent on breaking my 5 day record this time and making it to 6 as I have tried and failed a few times now. Sometimes I just crack at 3 days while aiming much higher. I actually had to hide food from myself - moved all sorts of things right to the top shelf out of sight, which can't be reached without a chair. The cracking has sometimes happened as I am there one evening and just feeling not so wonderful, fasted, and I open the cupboard and there in front of my eyes are tins of something or other. I stare at it, open and close the cupboard a few times over half an hour and stare at it then crack. So helped having it not visible. It's really bad to crack late at night with tins of stuff as well, left me in a nasty mood last time it happened.

This was the first time I used yohimbine while fasting. Realised one day when it raised my pulse that I was forgetting to do the thing you are supposed to do which is slow cardio 40 minutes after taking it, after it has entered the system and quickened the pulse. If you just sit there as I did the first few times I took it, you're wasting it as to maximise fat loss while fasted and on yohimbine you need to get your blood flowing.

This does feel like madness at times but I feel my days of doing fasts that are longer than 2 days will soon come to an end as I will hit my target weight. Once during the week I had to lie down after waking too early and being generally exhausted from it. Also after the refeed I had to lie down for a while but apart from that, felt relatively normal most of the time except for that 'fasted' feeling in the head and not being bounding with energy to run around for example. Have not told anyone about this, apart from writing it on the forum and may not do so in a rush either. They always have something to say, and not always necessarily encouraging either.

 

[Australia Sucks]

I have done many lengthy fast cycles over the past 4+ years. I usually do it after I gain weight (due to eating too much garbage, which i need to stop at some point) and need to lose weight to get back to normal.

I have done fasting cycles anywhere from 2 days all the way up to 28 days on one occassion. Currently I have recently been doing 3 - 4 day water fast cycles for over one month now to lose weight. I am currently in the middle of an 18 day water fast.

Something to note for those who are new to longer fasts is that you will also lose a lot of water weight which will come back when you start eating carbs again so you won't know exactly what your weight really is until 3 or 4 days after a fast ends.

 

[Australia Sucks]

I am thinking of doing a 3 day fast for the start of Great Lent, if I get a blessing to do so.

I've done 24 hours before, but nothing beyond that. I am a bit conscious of not over doing it. Any recommendations for doing your first 3 day fast? I am prone to getting headaches (I had one pretty bad during my last 24hr fast) I am hoping to avoid this again if possible, if anyone has any tips?

Thanks

My advice for longer fasts would be to build up to it.

If you have concerns about a 3 day fast and you have already done 24 hours, next time stretch the fast to 36 hours, Then the time after that 48 hours. Then the time after that 60 hours. Then finally you can do a 72 hour (3 day) fast.

Although personally I still think 3 days is not such a big deal and you could do it straight off the bat, but the above advice makes it a little easier for fasting novices.

 

[Australia Sucks]

It will not just switch back on again in an instant like a light. It's like you need to 'tickle' it back to life over perhaps a 6 hour period. So I think my vegetable soup with beef broth and small strips of meat does that better than a steak.

Your body kind of does this automatically for you. When you come off a long fast and start eating again you will see that your appetite is much less and you become full very quickly. Usually it takes at least a day for your appetite to fully return after an extended fast. Also concerns about refeeding syndrome are overblown. Its very rare for it to actually happen.

 

[stadtaffe]

My life has not been quite right for fasting lately, but at the moment I took the opportunity to repeat something I have done once before - staying in a remote cabin and deliberately not taking enough food with so that it runs out and I effectively start fasting, like it or not.

This time, there were a number of items here other people had left behind including black pepper, chili flakes, juniper berries, dried onion seasoning. After a few days in the absence of anything else, they become appealing.

I looked it up and it turns out that juniper berries become poisonous, can damage the kidneys, if you consume them in quantity rather than just let them stew and add flavour to things. Some kind of oil that causes damage to the kidneys and other problems.

So after several days I have inadvertently fasted, no lasting ill effects from the chilli flakes, pepper, juniper. Were some mild and worrying pains going to sleep last night which I attribute to the juniper however.

The moral of it is that at times you lack the will power, you can bring about fasting by isolating yourself in nature far away from any shops and without transport and deliberately running out of food. Just that if you do that it is best not to have things sitting around which are tempting but basically inedible.

 

[stadtaffe]

I've now run both a fasting and a lifting experiment. I lift anyway but upped the amount significantly for a while.

For the lifting, it was about a month of at least 4 times a week of weights and protein oriented diet.

The fasting involved periods from 2 to 6 days at a stretch with just electrolyte water ("snake diet"), black unsweetened coffee and tea and some supplements notably yohimbine, also about a month.

In retrospect the fasting had a greater effect on my physique over a time frame of weeks.

Yes, was great to put on muscle and be lifting a bit more weight week by week, but the changes from the lifting compared to the fasting phase were not as drastic.

I suppose it's cutting and bulking and you simply need phases of both but in my case, the cutting seems to have greater effect.

 

[stadtaffe]

Sorry, I don't normally do this but a small woe is me story. Have been suffering, even if maybe self-inflicted. Fasting gone wrong

I ran out of potassium chloride for the electrolyte water / snake juice. Where I am currently staying it is "prescription only" ! That I believe because some people can cause themselves heart problems by overdoing it. Damn nanny state..

So I was going to go to a doctor to try to get a prescription but instead realised that if I travelled not that far and crossed the border into another country it should be available over the counter. It's probably like that in America with the states. So I put the plan in motion and will hopefully be collecting my powder within a few days. A big quantity this time.

But I couldn't wait to fast after what the scales were saying following some recent travel and social eating.

So I started fasting and 48 hours into it found a jar of herb salt and started eating it in large quantities out of the jar. Somehow I thought I could just compensate for the missing potassium with extra sodium and it wasn't as potent as pure salt.

Then I was drinking lots of water.

Then when it was over I was at least a kilo more than at the beginning!! Broke the fast a bit shy of 72 hours in a bad and sleepless way after too much coffee. Very rare that I manage to have so much coffee later in the day so as to cause that.

But to look at the digits at the scale and see it so higher than when you started after not eating for days, even when you know it's water not fat, is not pleasant.

Then the next day I have a very unpleasant feeling in my head and read :

What Happens If You Eat Too Much Salt?

Signs And Symptoms Of Too Much Salt Intake

Symptoms of too much salt intake are feeling dehydrated and thirsty, infrequent urination, high blood pressure, obesity, kidney stones, and gastritis.

curejoy.com

As per research cited by the Centers for Disease Control, there is a “close-dependent relationship” between too much salt intake and high blood pressure. Consuming high amounts of sodium makes our bodies retain water in our bloodstream and that raises the volume of blood in our bodies. This leads to high blood pressure (hypertension), which in turn can damage the arteries and organs, particularly our brain, kidneys, and eyes.

Hypertension and prehypertension also increase the chances of suffering heart attacks, strokes, kidney disease, and eye problems.3 And if that’s not worrisome enough, the American Institute for Cancer Research holds that high salt intake is a likely cause of stomach cancer.4

Other studies have shown that high sodium levels can cause cognitive decline in older adults.

Oh no what have I done, what was I thinking Wish I had a blood pressure meter to check.

That is interesting - retain water in bloodstream, raises volume of blood, raises blood pressure. Really better not mess around with salt (sodium) like that again that was a bad idea. Going without food can drive a person to do unusual things.

At least I now have an explanation for this horrible feeling in my head - hypertension.

Apparently potassium cancels it out -

Potassium lowers blood pressure - Harvard Health

When it comes to fighting high blood pressure, the average American diet delivers too much sodium and too little potassium. Eating to reverse this imbalance could prevent or control high blood pres...

www.health.harvard.edu

Hope all goes to plan with getting hold of this powder. I'm tempted to avoid sodium for a several days after that. Will just keep drinking a lot of regular water and hope it goes away soon. Maybe do some cardio and try to sweat it out. If you're doing snake diet, stick to the recipe..

 

[bubs]

I’ve been doing intermittent fasting (restricting eating from 11am to 7pm) for a little over a week now. Drink about 2 cups (16oz total) of black coffee before 11am. I haven’t been strict at all with diet during the 8hrs. Mostly healthy foods and some bad snacks (chocolate candy bar afternoon snack, a beer with dinner), but this is consistent with before, just compressed into 8 hrs a day.

What I’ve noticed so far:
1) Gained 2-3 lbs in this week. (I’m fairly lean already…5’9” and in the low 150’s). Exercise has been moderate and consistent as before. This surprised me because I feel like skipping breakfast and no cream/raw honey in my morning coffees, I think my overall daily caloric intake is equal or less. So a little confused about the slight weight gain but seems to have leveled the last couple days).
2) Bowel movements - Similar to when I did carnivore diet for 10days, I have less frequent bowel movements (usually 1-2 per day but on diet it’s 0-1 per day). Also the “quantity” is much less and harder less mushy as well. Sorry for graphic description.
3). Haven’t noticed anything else different.

 

[stadtaffe]

I’ve been doing intermittent fasting (restricting eating from 11am to 7pm)

Good luck.. I'm not winning so much at this myself at the moment. Almost posted here a few times recently. My biggest struggle has been the sleep torture involved with fasting, not falling asleep and then waking too early. Then you're awake at 4am while everyone else is asleep and staring at a cupboard containing food you must not eat.

restricting eating from 11am to 7pm

I think you mean "restricting eating to 11am to 7pm" as from makes it sound like the opposite.

I’m fairly lean already…5’9” and in the low 150’s

It sounds like about where I am, just trying to lose the last little bit.

So you eat from 11am to 7pm. I can say with my horribly low metabolism that alone would do nothing. That is barely deviating from regular eating anyway. If you sleep from 11pm to 7am, and you're not eating while asleep somehow, the only eating you are avoiding with that regime is the 4 hours before bedtime and a further 4 hours in the morning.

If we were obese fatties who did nothing but eat 24-7 cutting out those 8 hours per day may have an impact, but sorry to be the bearer of bad news, it's not enough to go from fairly lean to cut.

You need to either be very controlled with that daily eating window, or permit that window only every second day and fast every second day. That is what I have been doing, but have been cracking mainly because of the sleep impact lately. Even though I managed these long fasts up to 6 days earlier in the year, am really struggling with it at the moment. Might have to leave it till I have a better frame of mind for it..

a beer with dinner

You can't do that and expect to drop weight! Certainly not as a daily thing..

 

[bubs]

Good luck.. I'm not winning so much at this myself at the moment. Almost posted here a few times recently. My biggest struggle has been the sleep torture involved with fasting, not falling asleep and then waking too early. Then you're awake at 4am while everyone else is asleep and staring at a cupboard containing food you must not eat.

I think you mean "restricting eating to 11am to 7pm" as from makes it sound like the opposite.

It sounds like about where I am, just trying to lose the last little bit.

So you eat from 11am to 7pm. I can say with my horribly low metabolism that alone would do nothing. That is barely deviating from regular eating anyway. If you sleep from 11pm to 7am, and you're not eating while asleep somehow, the only eating you are avoiding with that regime is the 4 hours before bedtime and a further 4 hours in the morning.

If we were obese fatties who did nothing but eat 24-7 cutting out those 8 hours per day may have an impact, but sorry to be the bearer of bad news, it's not enough to go from fairly lean to cut.

You need to either be very controlled with that daily eating window, or permit that window only every second day and fast every second day. That is what I have been doing, but have been cracking mainly because of the sleep impact lately. Even though I managed these long fasts up to 6 days earlier in the year, am really struggling with it at the moment. Might have to leave it till I have a better frame of mind for it..

You can't do that and expect to drop weight! Certainly not as a daily thing..

I’m not trying to drop weight, just seeing if the intermittent fasting helps with inflamation (I have arthritis that flares up every couple days), and IB issues and they may be related to inflammation. Haven’t noticed any changes to arthritis pain, but the intermittent fasting (and a 10 day test I did of carnivore diet), seem to help some with intestinal issues I’ve had.

 

[stadtaffe]

arthritis that flares up every couple days

I had a relative when I grew up who had it, so hope that does not mean I will get it one day. They were adamant about avoiding the 'nightshades'. You've probably heard about that.. I just looked it up and can see they were not alone in this theory :

Arthritis and Nightshades: Is This Making Inflammation Worse?

The arthritis and nightshades connection: Eliminating a specific plant group from your diet could ease inflammation and provide arthritis relief.

bodyecology.com

potato, tomato, eggplant, bell peppers, chilli peppers, tobacco

Article goes into some detail in replacing those with other food items.

 

[bubs]

I had a relative when I grew up who had it, so hope that does not mean I will get it one day. They were adamant about avoiding the 'nightshades'. You've probably heard about that.. I just looked it up and can see they were not alone in this theory :

Arthritis and Nightshades: Is This Making Inflammation Worse?

The arthritis and nightshades connection: Eliminating a specific plant group from your diet could ease inflammation and provide arthritis relief.

bodyecology.com

potato, tomato, eggplant, bell peppers, chilli peppers, tobacco

Article goes into some detail in replacing those with other food items.

Interesting, I’ve been trying to identify foods for several years that may trigger the arthritis spikes. I’ve had a few suspects on this list but never could find consistency. Potatoes (potato chips specific was a suspect food) and chili (that has various peppers mentioned as well as tomatoes and tomato sauce). I’ll look to cut all of these out for a few weeks and see how it goes. So far it seems like I’ll have a few days with minimal issues then a few days in a row with pain. Ironically most of the pain occurs at night while I sleep. Fingers, Hands and wrists, my one bad shoulder and pelvic area/hips are my zones that flare up. Usually 10 minutes up in the morning, most of it subsides.

 

[SCW]

On day 3 of another (hopefully) extended fast. I've gain back quite a bit of weight since my last post here and my wife reports that I've begun to snore again. I know that I've been eating more than I should, as I love to cook and snack.

Day 1 was miserable, stomach growling and a depressed mood.
Day 2, I was having trouble sleeping at night, thinking about all the things I want to cook and eat. (On the plus side, these thoughts drowned out the usual lustful ones).

Day 3, so far I've woken up and had a cup of bulletproof coffee (coffee + ghee + MCT coconut oil) and finally feel more mentally calm. I don't consider this a break in my fast as it's not a real "meal", and the consumption of fat should help my body get into ketosis, as well as managing my cravings.

The plan is to continue to day 4 tomorrow, day 5 there is a dinner I cannot avoid, with the intention to continue fasting afterwards.

 

[bubs]

On day 3 of another (hopefully) extended fast. I've gain back quite a bit of weight since my last post here and my wife reports that I've begun to snore again. I know that I've been eating more than I should, as I love to cook and snack.

Day 1 was miserable, stomach growling and a depressed mood.
Day 2, I was having trouble sleeping at night, thinking about all the things I want to cook and eat. (On the plus side, these thoughts drowned out the usual lustful ones).

Day 3, so far I've woken up and had a cup of bulletproof coffee (coffee + ghee + MCT coconut oil) and finally feel more mentally calm. I don't consider this a break in my fast as it's not a real "meal", and the consumption of fat should help my body get into ketosis, as well as managing my cravings.

The plan is to continue to day 4 tomorrow, day 5 there is a dinner I cannot avoid, with the intention to continue fasting afterwards.

I have a friend who does keto 3-4 days straight every week. Doesn’t work for weight loss. He yo-yours weight all the time. I think I’m convinced you just have to reduce your portion sizes and calories as a daily all-time thing to truly lose weight and stay leaner.

 

[SCW]

Day 4 finished yesterday, not sure if I'm having trouble sleeping, or am just more alert, just lying in bed during normal sleeping hours but mind racing with thoughts, not even feeling sluggish.

Looking up a bit more information online I found this: https://www.drberg.com/blog/6-stages-of-fasting

The 6 stages of fasting​

Caloric restriction offers impressive benefits when practiced correctly, as each fasting stage induces a specific set of physiological changes that can contribute to significant health improvements.

Here are the six distinct stages of fasting.

8–14 hours​

During the initial stage of fasting, your body relies on available blood sugar and begins depleting glycogen stores, which are reserves of glucose stored in the liver and muscle cells.

After around 10 hours of fasting, blood sugar and glycogen levels are declining, which inhibits the release of insulin, a critical metabolic hormone involved in blood sugar regulation and fat storage.

“When insulin levels drop, the body starts to initiate fat-burning by releasing fatty acids from fat cells,” explains Dr. Berg. “This shift moves the body from relying on sugars and carbohydrates as fuel to using stored body fat as its primary energy source.”

14–24 hours​

As fasting progresses beyond 14 hours, the liver starts converting stored fat into ketone bodies, a group of organic acids that serve as a highly efficient fuel source when glucose is limited.

Research published in Nutrients found that ketones have neuroprotective properties linked to enhanced cognitive function, including mental clarity, memory recall, and problem-solving.

This likely explains why many individuals report heightened focus and concentration, reduced anxiety, and better moods during extended fasting periods.

Due to their appetite-suppressing effects, ketones not only support brain function but also help reduce hunger and cravings, making it easier to continue fasting.

At around 16 to 20 hours of fasting, the body triggers autophagy, a cellular repair process that removes and recycles damaged cellular components. This promotes overall cellular health and contributes to longevity by rejuvenating the body at the molecular level.

24–36 hours​

Between 24 and 36 hours of fasting, the liver starts to burn fat more effectively. This leads to a surge in ketone levels in the bloodstream, signaling the onset of ketosis.

During this phase, fat burning intensifies as the body relies primarily on fat stores for energy, which explains why fasting for 24 hours and longer is associated with a significantly increased capacity to lose weight.

In addition, evidence published in Applied Physiology Nutrition and Metabolism found that fasting for 48 hours increased the concentration of brain-derived neurotrophic factor (BDNF) by 250 percent.

BDNF is a critical protein that plays a crucial role in supporting brain health by promoting the growth, maintenance, and survival of neurons.

Furthermore, BDNF helps stimulate the regeneration of brain cells and has been linked to a reduced risk of neurodegenerative disorders such as Alzheimer's and Parkinson’s disease.

36–48 hours​

As fasting extends into the 36 to 48-hour range, advanced autophagy takes place. This not only aids in cell regeneration but also provides essential amino acids needed for physiological processes, minimizing the need to break down muscle tissue for protein synthesis.

Research published in the International Journal of Molecular Science summarizes the protein-sparing effects of autophagy as follows, “During nutrient deprivation, autophagy is enhanced to maintain a provision of important proteins and other nutrients to serve as an energy supply, thereby increasing cell survival.”

Additionally, when the liver isn’t occupied with processing nutrients, it can more efficiently clear and eliminate toxins, environmental pollutants, and metabolic by-products.

This enhanced detoxification capacity is associated with better liver function and helps lower oxidative stress and inflammation, which is linked to a reduced risk of cancer, cardiovascular disease, liver problems, and metabolic disorders.

48–60 hours​

Fasting for more than 48 hours often induces a heightened sense of energy and mental sharpness and may be especially beneficial for those seeking to improve and optimize their metabolic health.

As insulin remains low due to a lack of dietary carbohydrate intake during extended fasting, cellular insulin sensitivity improves. This enhances cellular responsiveness to insulin signaling, which supports optimal blood sugar control and may help prevent and reverse insulin resistance.

Poor blood sugar control and insulin resistance are the main drivers of serious health issues, including obesity, metabolic syndrome, diabetes, and heart disease.

Fasting exposes the body to physiological stress, which triggers survival mechanisms such as autophagy and growth hormone release.

Increased growth hormone production helps mobilize fat stores for energy production, maintains muscle mass, and supports the regeneration of cells and tissues.

60–72 hours​

Approaching the 72-hour mark of a prolonged fast can trigger a mix of physical and mental fatigue but also a profound sense of accomplishment and rejuvenation.

In addition to accelerated fat burning, the body undergoes remarkable changes in immune system function during the final stages of an extended fast lasting up to 72 hours.

A study published in Cell Stem Cell found that a 72-hour fast can help clear out old, damaged, and dysfunctional immune cells and stimulate the production of new immune stem cells, enhancing the body's ability to fight infections and recover from illness.

The authors propose that prolonged fasts could be particularly beneficial for individuals undergoing chemotherapy, as this may reduce treatment-related cellular damage and enhance recovery by supporting the renewal of critical immune defenses.

The body’s ability to renew immune cells, stimulate cellular repair mechanisms, and promote healing is one of the most profound benefits of extended fasting.

If 72 hours is the limit, then it seems there's no meaningful benefit of prolonging it for a very extended period. After 4 days (96 hours) I felt I was ready to break my fast.

Weighed myself this morning and saw that I've lost 11 pounds over this period.

Afterwards, I enjoyed a bowl of noodles with beef and eggs, and felt much better for it.

I believe fasting will remain an important part of my life, especially given the immune, anti-cancer and autophagy effects in addition to ketosis and weight loss, but needs to be approached with a sense of preparedness and readiness.