How long can you safely do a dry fast?

How long can you safely do a dry fast?


One of the most important questions when it comes to dry fasting. How long can you safely do it?

Table of contents

What is the ideal time for a curative dry fast? No one knows. Some people claim that the longer you go, the more healing will be done. I argue that that may not always be the case. Yes, going longer usually means more autophagy or deconstruction, but at what cost to the rebuilding constructive phase? Can you go so far that you potentially damage benefits from the refeed and stem cells? In fact, the refeed is more important to healing than the fast in my opinion. Both are necessary, but it's actually the stem cells that rebuild that which has been damaged. So is there a limit to how far you should fast? Is it until you pass both acidotic crises? Personally, I think the ideal length that you can and should safely dry fast depends on the individual, their fasting muscle, their weight, their illness, and their goals. Nevertheless, I also believe that going over 9 days is not necessary, and frankly may cause more bad than good. I am a fan of fractional fasting, and I am a fan of refeeding correctly. In this chapter, I'll do my best to answer questions related to how long can you safely do a dry fast.

Please look up the Scorch Protocol to see an example of daily foods and supplements recommended in between dry fasts during the refeed. The scorch protocol currently is where the most up-to-date information is being distilled from over 200 pages of notes and data from other dry fasters. It includes a preparation protocol, an inside fast protocol, refeed protocol, an in-between fasts protocol, and a sleep protocol to combat sleep problems and insomnia-esque dry fasting periods. A lot (if not all) of autoimmune diseases can benefit from the scorch protocol

What is dry fasting?

The obligatory "What is dry fasting" introduction. This is for those new to it who have stumbled upon this article. Dry fasting is the abstinence of both food and water. Normally when people think of extreme fasting they think of people drinking water only and possibly adding things like electrolytes or black coffee and tea. When it comes to the dry version, removing all forms of food and water, and living on air alone is something that most people consider impossible. Yet dry fasters are alive and in most cases, thriving. In fact, most fasters who eventually try dry fasting, never look back. It's that good. Just make sure you know the ins and outs before attempting it. When you dry fast you accelerate autophagy to unimaginable levels. You also pull toxins out of cells at an increased rate. Water fasting on the other hand makes it so that your digestive system never takes a complete rest, and your cellular water never gets a deep clean. The most powerful aspect of a dry fast is the unique hormesis or "bodily stress" that occurs without water. This triggers a bounce-back response that increases stem cell production massively. Dry fasting is powerful, and with great power comes great responsibility. Dry fasting should not be performed until you have tried water fasting first, and should only be started with short dry fasts in the beginning. Now let's get back to the main topic of "How do you break a dry fast properly?"

Different people will give you different recommendations on the maximum duration for a dry fast. Filonov used to recommend 9-11 days, he now recommends 7-9 days. He also does fractional fasting with a 5-day, 3 weeks refeed, into a 7-9 day. Schennikov recommends an 11-day dry fast. August Dunning recommends a 7-day dry fast once or twice a year. Lavrova recommends cascade fasting.

It used to be said that you can safely dry fast for only 3 days, as per the 3-3-3 rule. 3 weeks without food, 3 days without water, 3 minutes without oxygen. It has recently been modified to 5 days dry, according to a few research papers indicating that patients dry fasted for 5 days without any negative health effects. Granted these patients were not doing any strenuous activities during the dry fast. The conclusion of the research paper states that "The intervention of 5 FWD days in 10 healthy adults was found to be safe, decreased weight and all measured circumferences, and improved renal function considerably."

Anthropometric, hemodynamic, metabolic, and renal responses during 5 days of food and water deprivation - PubMed
The intervention of 5 FWD days in 10 healthy adults was found to be safe, decreased weight and all measured circumferences, and improved renal function considerably.

If we go by this specific research paper, we can say that it seems that a 5-day dry fast is the current safe duration if precautions and preparations are put into place. According to this experiment, the 10 participants did not prepare in any different way, right up until the dry fast they ate what they regularly ate. They also went for a daily walk of around 30-60 minutes and followed their daily activities at a moderate level of intensity. Afterward, they refed carefully for 3 days, starting with water and then some juice, fruit on the second day, and a light meal on the third day.

What does this mean? It means that, according to this paper, it seems that a 5-day dry fast is safe enough that it does not warrant too much preparation in advance. This is something that seems counterintuitive to the idea that 3 days without water equals death. Yes, granted that someone is in a terrible environment and performing strenuous activity, the 3-day concept starts to make sense. But keep in mind that the participants in the study still maintained moderate activity.

If you are relatively healthy, you can still garden and do chores, even if you feel weak.

While you are dry fasting you may notice that you get lightheaded and dizzy when you get up too quickly. This usually causes you to stress out and to worry, which in turn spirals you into negative thinking and you start attributing it all to being dangerously dehydrated. What this usually means is that your glycogen levels are dropping or have dropped, meaning your water levels are pretty low, and in turn, your electrolytes are low.

These 3 things play a big role in the lightheadedness from sudden movements and standing up too quickly. Your muscles utilize glucose for quick movement while ketones are used for sustained movement. Don't forget that your body also produces glucose from gluconeogenesis, the act of converting glycerol and amino acids into glucose. During a dry fast, it creates just enough glucose to maintain bodily functions, so think of it like a thin layer of glycogen that allows you to do some quick movement, but that will take longer to replenish than normal. While not fasting, you have a reserve of glycogen ready to be transformed into glucose very quickly, but while fasting you don't have that reserve, so you have to think of it like a sustained burn. If you overdo it, you'll feel very very depleted, but don't panic. The best thing you can do for this is to lie or sit down and relax. Give your body time to re-establish homeostasis. This goes for the mental issues as well. There will be waves of feeling good and bad, if you prepare for them you'll have an easier time riding them out. A good mantra to repeat to yourself when the going gets tough is "This too shall pass".

How does the length of a dry fast affect potential health benefits and risks?

There are two acidotic crises that can occur. They are usually around day 3 and day 7. By going through them, you pass a hormetic threshold. Hormesis is the ability your body has to bounce back from stressors. So if you can dial in the correct amount of stress on the body, you can get a very beneficial bounce back. This is seen in lots of stresses that people subject themselves to, to get health benefits. Think of heat stress like sauna, cold stress like cold water, muscle stress through physical exercise, and mental stress like meditation. In each of these scenarios, it's possible to overdo the stress and actually cause negative effects. Maybe not with meditation, but you can still burn out.

Finding the right balance of hormesis is key. If you look at this graph posted about fasting benefits over time you see that some people are using it as an argument that there are little to no benefits of fasting longer than 5 days. This is because as the blood glucose levels drop and stabilize around day 4, your autophagy falls down, and everything else stabilizes. If we assumed this graph is correct, does it indicate that you should start from a high-carb diet to get the maximum benefits of a dry fast? You could argue that. If you are chasing macroautophagy. And to some extent microautophagy. But this chart fails to recognize that there are different types of autophagy and in this case completely ignores mitophagy, chaperone-mediated autophagy, and ribophagy.

As the length of your dry fast progresses, your body enters into deeper ketosis. Obviously, there's an upper threshold limit to how many ketones you can produce per hour, and it's possible that the limit is reached within 5 days. What this graph and others fail to take into consideration is that these high levels of ketosis are maintained once reached. Yes, some slight changes occur when acidotic crises are overcome, but the point stands. While maintained, we reach max level lysosomal activity. This means that our lysosomes are supercharged. Lysosomes require an acidic environment to function. Think of them like crocodiles that require the sun and heat because they are cold-blooded animals. Lysosomes require acidity in the same manner. When you enter ketosis, the breakdown of fat into glycerol and fatty acids occurs. The name fatty acid implies it is acidic, and yes it creates an acidic environment. Most of the time our body is constantly trying to maintain equilibrium, so that's where a lot of the benefits come from. The stress is induced on the body while it tries to maintain balance. This is also where the acidotic crisis power comes from.

So in reality, there's not enough research to really know the ideal times. We need more research. We have to be aware that the longer the dry fast goes on, the more dangerous and risky it becomes. At this point, it is pretty safe to say that the average human body can quite easily handle a 5-day dry fast. The equilibrium in blood plasma solutes was maintained, and overall improvements were recorded even in kidney health. However, we know that mitophagy is mostly stimulated through starvation and hypoxia, while microautophagy, ribophagy, and chaperone-mediated autophagy are stimulated through starvation and hyperosmotic stress. Hypoxia is the absence of oxygen. We don't lose oxygen during a dry fast right? Well, considering a hyperosmotic state (which is what a dry fast achieves and deepens) means that the blood gets thicker and draws water out of its surroundings (cells), which means that blood flow slows down. We create a hypoxic environment by dry fasting as a secondary effect. Oxygen still reaches the cells, but in less consistent amounts, sort of like a calculated stressor. Think of it like someone controlling a dam and releasing water at a slower pace. You'll still get your water, you just can't gorge on it. This is different from an actual hypoxic environment where no oxygen is delivered and the cell dies or gets transformed in a way to deal with the anaerobic environment.

Filonov and other Russian doctors can claim to have seen the biggest benefits with X amount of days, but we don't know if the biggest immediate cure is better in the long term, or if the shorter but more often fasts are preferable. We don't know the damage of pushing dehydration to absurd limits can cause. We do however know that there are powerful anecdotes of people healing with 9-day dry fasts, while some psychos push it to 15 (looking at you, Trevor;). I've personally done a 9 and an 11-day hard dry fast and to be honest, I'm not a fan. Read about my 300 Days of Dry Fasting Insights.

Here's the Yannick dry fast deep healing days calculation to take into consideration: After 60-72 hours you reach the chaperone-mediated autophagy level. It's at this level, the most powerful deconstruction starts to occur. Chaperone-mediated autophagy is the strongest form of autophagy. It's in this time frame that I start counting the days as maximum healing days. You can see that with this calculation you can achieve similar benefits of an 8-day dry fast by doing three 4-day dry fasts. The difference? About ~100 hours. Yes, I know the drawing shows 384 hours, but it should have been 288 hours. We also have to take into consideration the preparation and the refeed, it really adds extra time. What this means to say is that you can achieve similar healing, but it will take much longer, and each fast will need to break through the first 2 days of toughness before the body adapts to the glycogen depletion. You can ease the situation by starting it from a low-carb diet and already being in ketosis. In fact, this is one of the hacks being used in the scorch protocol. But be aware that if you're pushing for a long 7+ dry fast, you will need to hydrate with some low-carb juices as part of the preparation, so carnivore/zero-carb style diets won't work as well for those very long and deep dry fasts.

This isn't to say that two to three-day dry fasts don't do a lot, they do. If I were to gamble on an answer to "What is the overall best fasting duration that encompasses healing but also safety?" I would call for monthly 5-day dry fasts, and in extreme situations push for longer ones or upgrade it to two 5-day dry fasts every month (bi-weekly). If you are healthy and simply looking for general house cleaning, mitochondrial rejuvenation, and life extension, I'd have to go with Dunning and recommend a once-or-twice-a-year 7-day dry fast. There is always the stem cell exhaustion shadow looming in the background. We don't know enough about it, so if you're healthy, there's no point in pushing dry fasts too much. Just be safe. But if you're in a health situation that you need to get out of, it's worth pushing a little further. If you want to theory-craft for your specific situation, set up a chat with me and I'll gladly craft away with you!

Are there different guidelines for short-term versus extended dry fasts?

When it comes to short-term versus long-term dry fasts, you really have to take into consideration the timing of the refeed. A simple way to think about it is to realize that the longer you dry fast, the more important the refeed becomes. The refeed needs to be gentle, and there are a few different ways that people approach it. No matter what you decide to follow for your refeed two key things don't change. One - Always start with natural spring water when you break the fast. It's the first natural step in waking up the digestive system. You may be tempted to take fruit or coconut water, maybe some bone broth. But the safest and gentlest re-awakening is through water. Therefore, remember to break a dry fast, by turning it into a water fast. Now, the amount of time you should water fast after dry fast differs by who you talk to. For my protocol, I ask that you do a minimum of 6 hours of water fasting. This goes for any length of a dry fast that surpasses 24 hours. Why complicate things? Some people will argue that you don't need to do it on dry fasts that are shorter than 72 hours. If you're in a rush, sure make small adjustments from a reasonable standpoint, but if you're doing long dry fasts, remember that water is first. Sip it slowly, and only then should you transition to a liquid caloric diet. Always focus on digestibility first.

If you're doing under 24 hours of dry fasting, focusing on what you can eat is not worth the effort, as long as it is not processed and is full of nutrients. At these levels, your digestive system doesn't truly get a chance to shut down. Think of it like this. The first night, regardless of whether you started in the morning or the evening, will still have some form of digestion going on. It's only really when you enter the 36-hour fast that your digestive system gets to rest. Think of it like the second night of fasting. I will go ahead and make a statement that anything under 30 hours of fasting does not require a lot of planning UNLESS you are extremely toxic, and suffer heavy detox symptoms. With this exception, you also have to take into consideration your fasting muscle. If you have fasted before, you will know yourself better. This is why no matter what you should do a 2-3 day water fast first, before ever attempting a dry fast. It's the smart way to approach it. And you should always attempt dry fasting in stages. The body reacts differently to a 36-hour dry fast, then 72 hours, and then a 120-hour. Jumping straight into a 5-day dry fast is possible for a decently healthy individual with water fasting experience (as documented in the 5-day dry fast research paper). But it's not advisable.

When it comes to following a specific protocol like the Scorch Protocol on your refeeds, you may notice that it's catered towards approximately 5-day dry fasts. However, it can work for longer and shorter ones. Think of it like an accordion that can be stretched and compressed. Currently, as of this writing, I have not compiled the full 7-day refeed but the first ~5 days of it. If you are doing a shorter fast, imagine compressing the accordion. You should still go for the first day as is, but you can take a little bit of leniency when it comes to the food, and borrow a little from the following day. And if you're going for a longer one, follow the 4 days as they are, and then try to slowly stretch the 4th day and stack on some next-level digestibility options. Refer to my digestibility list in the scorch protocol.

Does the body's fat content influence how long one can dry fast safely?

Yes, and no. Sometimes someone who is near the underweight BMI can still dry fast successfully. It's actually surprising how low the body can go, and how much we overestimate/underestimate our fat content. If you are seriously underweight, something like skin and bones, then you need to figure out a way to fatten up. The goal of the dry fast and all extended fasting is to start deep ketosis, which requires fat burn. You need to release the fatty acids which eventually get turned into ketones, to both power your body, and increase the acidity in your body. This triggers most of the healing hormetic effects as well as stimulates the immune system and autophagy. If you have an impossible time gaining weight, there may be something off with your body and a water fast may be preferable to try to fix the metabolic pathways for gaining fat. There are also specific food combinations that help gain fat quicker such as sugar and fat together. Nature's fattening-up formula is raw cow's milk, so that is also something you can consider. If lactose is an issue, look into Kefir with natural sweeteners like honey, maple syrup, and blackstrap molasses.

A higher body fat content makes combined fasting easier. It also makes fractional fasting easier. Both of these are methods that make do with a shorter dry fasting timeframe but have powerful effects nonetheless.

For combined fasting, you usually look at 2-3 days of dry fasting followed by 7-10 days of water fasting. This is a way for the person scared of dry fasting to limit it to the beginning of the acidotic crisis (usually) and then continue in a method of fasting that feels safer to them (water). Because you have a higher fat content you can push the water fasting for a very long time and not worry about BMI.

For fractional fasting, you look at breaking apart a 9 or 11-day dry fast into two smaller dry fasts. Something like a 5-day into a 7-day dry fast. The effects are very similar, and some will even argue that the fractional fast is more powerful, because there is a compounding effect that builds even during the refeed. The way to conduct this is to refeed for a minimal amount of time in between, this means about the same amount of days as the days you fasted. In this case 5 days of dry fasting into 5 days of refeeding and then back into a 7-day dry fast. In fact, I truly believe this method is much stronger than a single 9-day or 11-day dry fast. I won't get into the details too much, but in these types of fasts you want to start from a healthy or overweight BMI because your refeed will be small amounts of food, where you should not be aiming to regain weight. You will undoubtedly regain a lot of water weight, but with a proper refeed you will gain minimal fat. Normally, the fat regaining is done after the refeed and before the preparation period.

How can you determine your body's tolerance and readiness for longer dry fasts?

Hard question. It really comes down to experience, diet, and fasting muscle. Men have an easier time than women, that's a fact. For a woman to get to 9 days takes much more perseverance and mental fortitude than a man. Women's bodies have a higher metabolic requirement especially pre-menopause. There may also be something evolutionarily where men may have had to go out for multiple-day hunts if they could not catch anything at first, while women stayed behind where the food storage was.

You can also test your body's tolerance and readiness for longer dry fasts by its ability to withstand things like the intestinal Epsom salt flush, or a liver flush. If you truly struggle with them, it may mean that you need to regenerate your organs and digestive system a little more before engaging in a really long dry fast. Read more about Intestinal cleanses for dry fasting here.

Dry fasting experience means that you understand your body and how it reacts to the acidotic crisis. It means you understand what days will be the hardest, and what to expect on each day. It means you know when to expect mood swings, and you can also experiment with different supplements and protocols to compare to previous dry fasting experiences. It also means that you prepare for the dry fast intentionally, and are aware that it's in your best interest to take digestibility into consideration when preparing and refeeding. In this world of dry fasting, experience is critical. A lot of new dry fasters commit a lot of early mistakes that set them back. The worst thing I see quite often is a new dry faster making terrible mistakes not knowing when to quit the dry fast. But something even worse is when they completely mess up the refeed. It's usually because of this that a new dry faster never dry fast again.

Your diet and experience with ketosis play a role in your body's tolerance for a longer dry fast. If you've never been in deep ketosis before you will have quite a shock once your glycogen stores get depleted. The body will give you a big WTF moment. This is an example of metabolic flexibility. A body that has not experienced ketosis will be confused when it comes to fat burning. Many people who constantly snack and eat high-carbohydrate foods will always have full glycogen stores. If your glycogen dips and blood sugar goes down, you may be in for a world of pain. This all goes to say that if you eat a ketogenic diet, carnivore, or intermittent fast regularly, your body knows what ketosis is, and has the ability to switch between glucose and fat burning much easier than someone who doesn't. This also prepares you better for fasting. Here's the kicker though. Even if you think you're a champ at intermittent fasting and keto, a dry fast can and will still kick your butt. The first time you introduce a hyperosmotic state, one filled with thicker blood and a very fast acidotic crisis, you may feel wrecked. It's for this reason that for most people it is recommended to take dry fasting in steps. Start with one day, move on to two, then three. So on and so forth. I personally prefer a faster approach and usually recommend going for 36 hours, into 72, into 120 hours instead. If however, you have severe illnesses that are contraindicated like diseases of the blood or kidneys, you should start off experimenting with longer water fasts or take it as a one-day progression. Sometimes to be even safer, you take it in 12-hour progression steps. One-day dry fast into one-and-a-half day, into two day, etc.

Another consideration is how much toxins you have stored in your fat cells. If you're coming from years of eating processed junk food and toxins, they will have accumulated in your fat cells. As you lose fat, the toxins grow in concentration in the blood. A dry fast equals very quick fat loss, so you can quickly get into a detox crisis characterized by extreme nausea and headaches. You may need to break the fast in these situations, refeed, and try again. This is because your body can only detox at a certain pace, and many times that threshold gets surpassed. The beautiful thing about this process is that each time that you refeed with good food, the fat that gets replaced is cleaner. That means that your subsequent fasts will be running on a higher percentage of 'better' fat. This fat will have fewer toxins and a much better nutrient and vitamin profile, compounding into an easier fast. This is part of the reason why people say that the fasting muscle is important because it also encompasses cleaner fat cells over time.

Dry fasting is not a joke. However, if you're young and looking for a rejuvenation hack to stay young longer, be faster, and smarter then you can tackle dry fasting with passion. If this is you, you've most likely already done fasts of varying lengths and have just discovered dry fasting. No matter what there are still mistakes that you should avoid because they can set you back, and in a worst-case scenario, cause damage that may be very hard to heal. If you are a self-experimenter and have your own anti-aging stack, set up a chat with me so we can compare notes and you can ask all your crazy questions.

What signs or signals should you watch for to know when it's time to break a dry fast?

Something that you need to take into consideration, but as a newbie to dry fasting you may not fully understand, in certain situations, you can take in some water and still continue your dry fast. Sure a hard dry fast is the absolute optimal version, but there are little leeways that you can take and still greatly benefit.

Extreme fear

If you have not dry fasted before you should not be pushing yourself too far too early. Without getting through the stages of dry fasting first, you will build up fear in yourself. This fear is not a joke. Mental is an important aspect. If you panic and continuously worry if you're going to survive this dehydration, you will activate negative stress responses in the body that can worsen your fast. Remember, people dying stuck underground are panicking and dying from thirst and hunger for 72 hours, yet we are doing the same thing comfortably because we are choosing to abstain. There's a difference, and the more you do it, the further you'll go, and the more you'll understand this concept. Sort of like an enlightenment.

pH in urine

pH in urine is a good indicator to see if you enter the acidotic crisis. If you're tracking your ketones and urine pH, you can see when you enter the acidotic crisis. A steady rise in ketones, sometimes sharply increases. The urine pH drops from baseline by about 1-1.5 points. Usually baseline is 7 and can be a bit lower if you are on a strong keto and low-carb diet. Once you clear the acidotic crisis it's possible to observe the pH go back up by approximately ~0.5 points. If your pH drops by 2 or more it may be a situation that needs to be looked at more closely with a few more data points.

Amount of Urine

amount of urine is a good indicator. If your body suddenly stops producing urine or is much less than your baseline (which should be established around days 3-4), then it is a signal that there may be some intoxication blockage and fat is not being metabolized correctly. Not many people use this strategy because it requires collecting urine, but it is a good tool for those who are curious and those who want to be extra cautious. You can also use this collection strategy to prove to others that your body does indeed keep peeing days after not having had any water, and you can also observe how the urine changes once you enter ketosis and after the initial glycogen and excess water dumping.

Heart rate over 120

This is your pulse. Heart beats per minute. The simplest calculation is to manually find your pulse by placing the index and middle fingers on the inside of your wrist, or on the side of your neck (carotid artery) just below the jawline. You count the amount of heartbeats in 10 seconds then multiply by 6. to get a full minute. During your dry fast, you may come into moments where your pulse goes as low as 40 or as high as 100. This is fine. But if your pulse is going extremely high or dropping extremely low and you feel horrible, both weakness and pain, then it's something to monitor. Sit down, relax, and count again. If it's above 100 for an extended amount of time, while resting, then we have a problem. You have two options. The first is to take a warmer bath with some magnesium flakes and try to relax. The second one is to take a little bit of warm or hot water (~125 ml) with a tiny amount of honey (1/4 teaspoon). This may be all it takes for you to be able to continue. Otherwise, if it stays up, or if you feel really bad and are mentally over it, break the fast and begin the water refeed protocol.

Insomnia over 48 hours of no sleep

If you really want to push the boundaries, you can extend this signal to 72 hours of insomnia. If you literally cannot fall asleep for 2-3 days straight, it's best to break the fast and give your body at least one month of refeeding and rebuilding before trying again. Something is seriously off with you, and be glad you're finally on the path of fixing it, just don't rush it. There are a few tips and tricks in the scorch protocol to deal with sleeping, but if none of them work, then breaking it is vital.

Intense unforgivable nausea, headaches, detox symptoms

Could be the lymphatic system not being drained effectively or overdosing on toxins, and the same goes for the blood as fat cells are releasing toxins. You need to remember that dry fasting affects electrolytes, dehydration levels, blood pressure, and blood sugar on top of all the toxin release. Sometimes it may be too much and the fast should be ended, then repeated once you are ready again.

The lymphatic system acts as a network of vessels and nodes that transport a fluid called lymph. As lymph flows through this system, it collects toxins, waste products, and unwanted materials from tissues. Lymph nodes, scattered along these vessels, contain immune cells that filter out harmful pathogens and produce white blood cells to combat infection. Eventually, the cleansed lymph is returned to the bloodstream through the thoracic duct, while the toxins are processed and eliminated by the liver and kidneys.

Is there a general rule of thumb for beginners who are trying dry fasting for the first time?

Start slow. Build fasting muscle.

Yogis recommend fasting on a certain day of the week according to the date of birth. This day almost always coincides with a good day for different horoscopes. -Filonov

I am running a poll on the Discord server to see if this concept works more often than not. Surprisingly a few people I've talked to have agreed with it. If you see the first day of the Discord poll, you'll notice 7 AGREE (the 1 disagree is my own because of how the poll needs to be structured). Personally, I am a Pisces, and Thursday has always been my favorite day to start a dry fast. I thought it was purely logical, it being the perfect day of the week to start a fast, and then suffer through Friday and Saturday. Now I'm second-guessing the Cosmere;)

What research or expert opinions provide insights into safe dry fasting durations?

A solid 5-day dry fast research paper is a good indication of water and food deprivation. We don't have research going further. There are Russian papers that you could get and translate if you were so inclined. This is something that I could perhaps collaborate with Sergei Filonov on.

Dry Fasting Physiology: Responses to Hypovolemia and Hypertonicity
Abstract. Objective: The aim of this study was to provide a deeper insight into dry fasting (DF) physiology. Design: Ten participants performed DF for 5 consecutive days. Methods: The following parameters were monitored daily: cortisol, aldosterone, high-sensitivity C-reactive protein (CRP), erythro…

JANUARY 20 2020 Ten participants performed DF for 5 consecutive days. K+ constant excretion was steady, Na+ excretion slowed down. Corroborates the idea that you should not eat sodium after the dry fast (including baking soda), but that supplementing potassium is highly recommended and may bring a lot of relief. Vitamin C has constant excretion and a half-life of 4.8 days. Eating Citrus right away is contraindicated through trial and error, possibly because your vitamin C levels are so low, that introducing such high amounts too quickly into a sleeping digestive system causes more negatives than positives. However good sources of vitamin C are recommended throughout the refeed (think cabbage raw, into lightly steamed broccoli, fruit = papaya). Highest increases in serum: Cortisol, Dopamine, Noradrenaline, Uric Acid (Gout).

Anthropometric, Hemodynamic, Metabolic, and Renal Responses during 5 Days of Food and Water Deprivation
Abstract. Background: Although there is considerable research in the field of fasting and fluid restriction, little is known about the impact of food and water deprivation (FWD) on body circumferences and vital parameters. Methods: During 5 days of FWD in 10 healthy adults, hemodynamic, metabolic, a…
5 days of FWD contain a triple risk: hypovolemia, hypertonicity, and hypoglycemia. However, our participants have tolerated the dry fasting well and none of them showed hypotension or any noteworthy disorder in HR, SatO2, electrolyte concentration, serum osmolality, and glucose level. It seems that a potent hormonal and nervous contra-regulation results in the effective management of FWD risks.
Hypertonic stress promotes autophagy and microtubule-dependent autophagosomal clusters
Osmotic homeostasis is fundamental for most cells, which face recurrent alterations of environmental osmolality that challenge cell viability. Protein damage is a consequence of hypertonic stress, but whether autophagy contributes to the osmoprotective…
The data document a general and hitherto overlooked mechanism, where autophagy and microtubule remodeling play prominent roles in the osmoprotective response (hormesis). Microtubules - lysosome pathways. Think of it as roads for transportation. The more you dry fast, the better the roads, and the stronger the subsequent fasts.
Protein misfolding in hypertonic stress: new insights into an old idea. Focus on “Genome-wide RNAi screen and in vivo protein aggregation reporters identify degradation of damaged protein as an essential hypertonic stress response”
Much effort has been directed to understanding how animals and cells adapt to hypertonicity. Most animals and cells are capable of adapting to extreme hypertonicity if hypertonicity is increased gradually over a sufficient period of time.
Ramadan Fasting Exerts Immunomodulatory Effects: Insights from a Systematic Review
Ramadan is the ninth month of the Islamic lunar calendar and is observed by Muslims as a month of fasting. All Muslim adults are expected to fast; nevertheless certain subgroups, including sick, frail subjects, and pregnant women, among others, are exempted.…
Increased fat catabolism sustains water balance during fasting in zebra finches
Highlighted Article: Water balance of birds fasting without water is maintained mainly by elevated fat catabolism, which generates 6 times more metabolic water compared with that for birds with access to water.
The researchers conducted a study with zebra finches, dividing them into three groups: one with unlimited access to food and water, one with access to water only, and one without access to either. After 24 hours, they measured the birds' metabolic rates and analyzed their body composition. Surprisingly, all the birds were well-hydrated, even the ones deprived of water. However, the body composition of the birds varied significantly. The water-deprived birds were able to generate an impressive amount of water by burning their own fat.

Dive deeper into metabolic water in this chapter: Metabolic Water and Fasting

How does dehydration risk factor into determining the length of a dry fast?

Activity level. Humidity. Diet pre-fast. Carnivore/zero-carb already puts you into a lower water state. That's why going for longer fasts of 7 and up is very difficult coming from a zero-carb diet. I recommend the zero-carb diet for fasts of 5 days and less, as an intense and powerful, but super easy way for beginners to get the most out of it.

Are there any tips for gradually increasing the duration of dry fasts to ensure safety?

Short dry fractional fast, recommended for those well-prepared and self-assured.

Fast for 24 hours (1 day) – eat for 48 hours (2 days)

Fast for 48 hours (2 days) – eat for 72 hours (3 days)

Fast for 72 hours (3 days) – eat for 96 hours (4 days)

Fast for 96 hours (4 days) – eat for 120 hours (5 days)

Fast for 120 hours (5 days) – withdrawal from dry fasting

How does one's age affect the safe duration of a dry fast?

It comes as no surprise that your age should be taken into consideration when dry fasting. Common prerequisites include being between the ages of 14 and 70. What does this mean for kids younger than 14 who may require dry fasting? Well, we enter into dangerous territory. We can dig into Ramadan practices and see at what age the religion allows the practice of fasting for children. Children must go through puberty before being allowed to practice Ramadan fasting. That would mean that the average age is ~13 or 14. This coincides with Filonov's reasoning of 14-70 as being the cut-offs. Does this mean you shouldn't dry fast if you are over 70 years old? I definitely do not agree, but having these boundaries allows you to be aware of the dangers. Being over 70 years old means that you need to take extra care when trying to fast. Especially if you've never done it before. It requires such a gentle approach that it's better to provide a blank statement like "Don't fast if you're over 70". It weeds out the people who don't want to do any research or have no self-control and will literally kill themselves attempting it. The ones who have discipline and understanding will be able to take the research that is currently out there and design the safest testing of dry fasting. This may look like doing the gentlest form of cleanses, eating carefully, and modifying the diet months in advance, Make sure they start with intermittent water fasting and water fasts, and once attempting dry fasting, they will start and increment it in little doses like 12 hour increases each new dry fast only.

Can menstruation impact the safe duration of a dry fast for women?

If you feel fine, it's perfectly fine to continue the dry fast when menstruating. You should not feel bad for having to shower in this situation, just remember to avoid getting water in the mouth. There are a few different strategies that women can employ to strategically start the fast and end it to coincide with menstruation. I may expand on this at a later date here or in a separate post. I highly recommend looking into Mindy Pelz's conversations on the topics.

How can one monitor their body's signals during a dry fast?

As mentioned earlier, I talked about the different symptoms you need to track and measurements that may indicate that you need to exit the fast to stay safe. However, here I'll mention what tools you can and should use for this. I'll start with the most important to least important.

  • Urine pH and Ketones measuring sticks. They are very easy to acquire, better to get multiple in one, instead of buying them separately. The one I use is called Urinox-10. This will allow you to measure your ketone levels which will tell you when you enter ketosis and deep ketosis. This along with a drop in urine pH can easily help you identify when you enter the acidotic crisis.
  • Blood Glucose Monitor. Some people use something like KetoMojo to get both blood ketones and blood sugar. I use Contour Next GEN which is a blood glucose monitor and requires an intelligent strip with each use.  
  • Digital Blood Pressure Monitor. Optional as you can use manual pulse counting as well, it's just simpler and more accurate, while giving you SYS and DIA to measure the pressure in your arteries.
  • A scale. Each day is slightly different but once you enter ketosis you can expect around 1kg of weight loss per day.
  • Body Temperature (optional) using a thermometer
  • Urine Collection in Mason Jars or other containers. You use this to observe your hydration levels and your ability to find baseline urination levels. One of the less known trackers for when to end the fast can be if your urine levels suddenly drop deep into a fast.

How often can one safely do prolonged dry fasts?

No one knows. Typically as long as you refeed and rehydrate long enough it should be safe. The minimum safest refeed length is 3 weeks but may be as long as 2 months since stem cell activity has been shown to increase for up to two months after a dry fast. Dunning recommends one to two 7-day dry fasts a year. No matter what, a cost-benefit analysis needs to be taken into consideration. If you are sick, and dry fasting is slowly improving your life, you will most likely continue it. If you are healthy, and doing this for longevity hacks and general improved health, you'll want to limit extended dry fasts to once or twice a year. I'd look deeper into Ramadan fasting and longevity studies.

Is it safe to dry fast during extremely hot weather?

It's not ideal. It's possible, but you'll need to stay out of the direct sun and may need to take some ice-cold baths/showers to cope with it. It comes down to common sense. Dry fasting is best done in colder weather. It is ideally done during fall-like temperatures, right before winter. You really do get hot on an extended dry fast. If you are doing less than three-day dry fasts, then it should be fine, as long as you make sure you stay out of the sun and don't do strenuous exercise.

Do hydration levels before starting the fast impact its safe duration?

Yes. Hydration is important. When going for fasts longer than 5 days, you should always make sure that you are hydrated well before the fast. This means that you had optimal amounts of spring water and juiced hard. You'll want to juice low-carb, this means staying away from high-sugar fruit juices and focusing on things like coconut water, celery/cucumber/ginger juices, and you can even throw in things like beets for a nutrient bomb (even though beets do have some sugar). If you start from a very low-carb diet with no juicing, you will most likely start on a slightly less hydrated level. This will make the first few days EASIER because your body will already be adapted to lower water levels and lower glycogen levels. You will already be in mild or moderate ketosis before entering.

Is it safe to do a dry fast while trying to conceive or during pregnancy?

Once again, this is common sense. You wouldn't drink or smoke while trying to conceive or during pregnancy. Even though dry fasting has hundreds of anecdotes of helping women conceive, it does so by improving the body through stress prior to conceiving. That means that you'll want to dry fast and refeed BEFORE you start attempting to conceive. I recently worked with a friend of a friend who had multiple miscarriages, and after taking a break and dry fasting they have just given birth to a baby boy! And of course, you won't want to dry fast during pregnancy, specifically extended dry fasting. However, there are some studies on Ramadan and pregnancy. Remember this is Intermittent Dry fasting, not EXTENDED dry fasting. I think it shows that Ramadan fasting does not greatly affect fetal development. Some studies have shown that it seems to have no effect on the fetus but it does positively affect the mother. I think any form of fasting during pregnancy is something that should not be done, just to be safe, but I am open to new research on the matter.

Is it safe to combine dry fasting with other types of fasting?

Dry fasting into water fasting is a very common hack that has been used a lot by Russian dry fasting doctors. A lot of people really like to prepare the body by water fasting a day before the dry fast. Personally, I'm not a fan, I prefer to go to the lightest meals and digestibility right before diving right into the dry fast. I do like to see a day of water fasting AFTER the dry fast, but the minimum is a 6-hour water fast afterward.

How do altitude, humidity, or atmospheric pressure affect dry fasting duration?

Humidity plays a big role. You can alter your dry fast if you use a humidifier. A pretty ideal humidity would be around 45%, but if you push this to 50-55% you will notice a difference in your dry fast. The higher humidity will lower perspiration, and because of that, water loss will be less. This will allow you to continue your dry fast with more ease, but it may also lessen its strength by a little bit. Hyperosmotic stress is one of the key drivers of dry fasting benefits. However, there is a sweet spot where you are already in hypertonic stress, and you want to extend it, while not going into deep dehydration. In my experiments, this is around 50-55%, but it should be focused on around day 5 for optimal healing, safety, and extension of a dry fast. The idea stems from dry fasting gurus who talk about the importance of sitting in a waterfall type of environment on really long dry fasts. They claim to absorb moisture from the air, which may be possible to some degree, but the slowed-down perspiration loss would most likely play a bigger role. Altitude plays a role as well since oxygen levels are reduced, resulting in slight hypoxia stress, which doubles down on the hypoxia stress already created from dry fasting, making mitophagy twice as pronounced. You also urinate more in high altitudes, which may speed up a dry fast, although there's not enough information about this. No matter what, a slightly cooler and less humid environment is always preferable for an extended dry fast.

Yannick Wolfe

15 Years of Fasting Experience, Ex-ME/CFS, Ex-Long covid. Tech Consultant, Molecular biologist, Father, Researcher, Experimenter.

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