Dry Fasting: Is It Worth It?

Today’s post is about dry fasting. I’ve covered plenty of other aspects of intermittent fasting, including recommendations around longer fasts, but lately I’ve gotten enough questions about this particular angle that I thought I’d address it.

Dry fasting is going without both food and fluid. That means no coffee, no tea, no broth, and no water or liquid of any kind (except the saliva you manage to produce). It’s an extreme type of fast whose fans and practitioners are adamant that it can resolve serious health issues. But does it? Is it safe? And what kind of research is available on it?

Where Does the Idea of Therapeutic Dry Fasting Come From?

The main proponent of dry fasting is a Russian doctor named Sergei Filonov. Filonov is still practicing from what I can tell, somewhere in the Altai mountains that span Central Asia. I found a very rough English translation of his bookDry Medical Fasting: Myths and Realities. Difficult to read in full because it’s not a professional translation, but manageable in small chunks.

His basic thesis is that dry fasting creates a competitive environment between healthy cells, unhealthy cells, and pathogens for a scarce resource: water. The dry fast acts as a powerful selective pressure, allowing the strong cells to survive and the weak and dangerous cells to die off. The end result, according to Filonov, is that the immune system burns through the weak cells for energy and to conserve water for the viable cells, leading to a stronger organism overall. He points to how animals in nature will hole up in a safe, comfortable spot and take neither food nor water when recovering from serious conditions, illness, or injuries that prevent them from moving around. But when they’re able to move while recovering from more minor issues, they’ll drink water and abstain from food. I’m partial to this naturalistic line of thought, but I don’t know if the claims about animal behavior during sickness are true.

Another claim is that dry fasting speeds up fat loss relative to fasts that include water. There may be something to this, as body fat is actually a source of “metabolic water”—internal water the body can turn to when exogenous water is limited. Burning 100 grams of fat produces 110 grams of water, whereas burning the same amount of carbohydrate produces just 50 grams of water.

Are There Any Dry Fasting Studies?

Unfortunately, we don’t have many long term dry fasting studies. In fact, we have one 5-day study in healthy adults. For five days, ten healthy adults refrained from eating food or drinking water. Multiple physiological parameters were tracked daily, including bodyweight, kidney function, heart rate, electrolyte status, and circumference of the waist, hip, neck, and chest.

Participants lost weight (over 2 pounds a day) and inches off of various circumferences, including waist, hip, neck, and chest. The drop in waist circumference was particularly large—about eight centimeters by day five. Blood pressure, heart rate, oxygen saturation, sodium and potassium levels, creatinine, and urea all remained stable throughout the study. Creatinine clearance—which can be a marker of muscle breakdown but also a normal artifact of fasting—increased by up to 167%.

The most voluminous research we have on dry fasting is the Ramadan literature. During the month of Ramadan, practicing Muslims complete a daily dry fast—from sunup to sundown—every single day. They eat no food and drink no fluids during daylight hours, which, in the countries where Islam originally arose, run about 15-16 hours. These are shorter dry fasts than the 5-day fast detailed above.

What happens to health markers during Ramadan? Mostly good things.

A 15- or 16- hour dry fast isn’t very extreme, even in the hot climates of the Near East. Two or three day-long dry fasts, particularly in hot weather, is another thing entirely. What works and is safe across 16 hours might not be safe or effective over three or four days.

I wonder if there’s a genetic component to dry fasting tolerance, too. Have populations who’ve spent thousands of years in hot, dry, desert-like climates developed greater genetic tolerance of periods without water? I find it likely, though I haven’t seen any genetic data one way or the other. It’s an interesting thing to ponder.

Is Dry Fasting Safe?

Obviously, skipping water can be dangerous. While we’ve seen people go without food for as long as a year (provided you have enough adipose tissue to burn, take vitamins and minerals, and are under medical supervision), going without water is a riskier proposal. The number I’ve always heard was three weeks without food, three days without water, though I’ve never really seen it substantiated or sourced.

One reason I’m skeptical of “three days” as a hard and fast rule is that most cases of people dying of dehydration occur in dire circumstances. People are lost out in the wilderness, hiking around in vain trying to find their way back to the trailhead. They’re thrown in jail after a night out drinking and forgotten by the guards for three days. They’re spending 24 hours dancing in a tent in the desert on multiple psychoactive drugs. These are extreme situations that really increase the need for water. Your water requirements will be much higher if you’re hiking around in hot weather bathing in stress-induced cortisol and adrenaline, or dancing hard for hours on end. Very rarely do we hear of people setting out to abstain from water on purpose for medical benefits, water on hand in case things go south, and ending up dehydrated. Part of the reason is that very few people are dry fasting, so the pool of potential evidence is miniscule. I imagine this last group will have more leeway.

Still, if you’re going to try dry fasting, you have to take some basic precautions.

6 Precautions To Take When Dry Fasting

1. Get Your Doctor’s Okay

Sure, most will be skeptical at best, but I’d still advise not skipping this step—particularly if you have a health condition or take any kind of medication. Diuretics (often used for blood pressure management), for one example, add another layer to this picture.

2. No Exercise

Avoid anything more intense than walking. For one, the hypohydration will predispose you to middling results, increasing cortisol and reducing testosterone. Two, the hypohydration may progress rapidly to dehydration. If you’re going to exercise during a dry fast, “break” the fast with water first and then train.

3. Keep It Brief

Yes, there was the 5-day study, but those people were being monitored by doctors every single day. I’d say 16-24 hours is a safe upper limit and probably provides most of the benefits (as Ramadan literature shows). Any longer, buyer beware. (And, of course, make sure you get fully hydrated in between any dry fasts you might do.)

4. Fast While You Sleep

Ramadan-style probably isn’t ideal from a pure physiological standpoint. The length (16 hours) is great, but the eating schedule is not. Those who observe Ramadan fasting ritual often wake up before sunrise to fit in food. They may stay up late to eat more. They go to sleep in a well-fed state, never quite taking advantage of the 8 hours of “free” fasting time sleep usually provides (and, of course, that’s not what their fasting practice is about). For a health-motivated dry fast, on the other hand, you should take advantage of it.

5. Take Weather Into Account

Hot, humid weather will generally cause the most water loss. Cold, dry weather will cause the least. Adjust your dry fasting duration accordingly.

6. Listen To Your Body

I’ve said this a million times, but it’s especially worth saying here. If you’re not feeling well during the dry fast, listen to your instinct rather than your agenda. (And don’t begin a dry fast when you’re ill. That should go without saying.) This is an optional tool. There are hundreds of other ways to serve your health and well-being. Don’t lose the forest through the trees because you’re drawn to a practice that feels more radical. Approach it smartly, but let your body’s intuition be the final arbiter.

That’s it for me. I haven’t done any dry fasting, not on purpose at least, and I’m not particularly interested in it for myself, but I am interested in your experiences. Do any of you do dry fasting? What have you noticed? What do you recommend?

As always, if you have any questions, direct them down below. Thanks for reading!


Mascioli SR, Bantle JP, Freier EF, Hoogwerf BJ. Artifactual elevation of serum creatinine level due to fasting. Arch Intern Med. 1984;144(8):1575-6.

Fernando HA, Zibellini J, Harris RA, Seimon RV, Sainsbury A. Effect of Ramadan Fasting on Weight and Body Composition in Healthy Non-Athlete Adults: A Systematic Review and Meta-Analysis. Nutrients. 2019;11(2)

Fahrial syam A, Suryani sobur C, Abdullah M, Makmun D. Ramadan Fasting Decreases Body Fat but Not Protein Mass. Int J Endocrinol Metab. 2016;14(1):e29687.

Aliasghari F, Izadi A, Gargari BP, Ebrahimi S. The Effects of Ramadan Fasting on Body Composition, Blood Pressure, Glucose Metabolism, and Markers of Inflammation in NAFLD Patients: An Observational Trial. J Am Coll Nutr. 2017;36(8):640-645.

Unalacak M, Kara IH, Baltaci D, Erdem O, Bucaktepe PG. Effects of Ramadan fasting on biochemical and hematological parameters and cytokines in healthy and obese individuals. Metab Syndr Relat Disord. 2011;9(2):157-61.

Saleh SA, El-kemery TA, Farrag KA, et al. Ramadan fasting: relation to atherogenic risk among obese Muslims. J Egypt Public Health Assoc. 2004;79(5-6):461-83.

Gueldich H, Zghal F, Borji R, Chtourou H, Sahli S, Rebai H. The effects of Ramadan intermittent fasting on the underlying mechanisms of force production capacity during maximal isometric voluntary contraction. Chronobiol Int. 2019;36(5):698-708.

Shephard RJ. Ramadan and sport: minimizing effects upon the observant athlete. Sports Med. 2013;43(12):1217-41.

TAGS:  Hype

About the Author

Mark Sisson is the founder of Mark’s Daily Apple, godfather to the Primal food and lifestyle movement, and the New York Times bestselling author of The Keto Reset Diet. His latest book is Keto for Life, where he discusses how he combines the keto diet with a Primal lifestyle for optimal health and longevity. Mark is the author of numerous other books as well, including The Primal Blueprint, which was credited with turbocharging the growth of the primal/paleo movement back in 2009. After spending three decades researching and educating folks on why food is the key component to achieving and maintaining optimal wellness, Mark launched Primal Kitchen, a real-food company that creates Primal/paleo, keto, and Whole30-friendly kitchen staples.

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63 thoughts on “Dry Fasting: Is It Worth It?”

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  1. Dry fasting is super hard for me, whenever I don’t eat I get reeeeeaally thirsty.
    All of your mention of fasting with water that I’ve seen also includes coffee and other noncaloric liquids. What’s your take on the difference between liquid fasting and pure water fasting, with regards to their benefits/effects?
    I’ve listened to podcasts with Dr. Rhonda Patrick and she is a proponent of anything except water breaks the fast because the body has to metabolize it/non water consumption starts the body’s clock, etc. I agree with her work, it makes sense, and I’d like to see your thoughts on the topic of water only fasting.
    Also, when I try to intermittent fast, skipping breakfast, I can’t do it if I consume coffee because it makes me jittery on an empty stomach. But I did do it successfully for a while and actually felt energetic when I tried it with just water.

    1. I had no trouble with hunger. It was obliterated. It was like the first week or so that you go into ketosis. NO MORE HUNGER. My thirst didn’t start rly till about 20hrs into it. But I’m always well hydrated. I just drink alotta water. Little coffe or tea that’s diuretic. I also made sure I had eaten the day or two before, I eat OMAD. Food has loads of water too.I wouldn’t go from a 3 day water fast to a dry fast. Well, maybe a short 24 hr one… ?

  2. The Yom Kippur fast is a 25-hour dry fast, which has been observed annually by Jews for millennia. I’ve done it many times. Other than a mild headache in the afternoon (more likely from caffeine withdrawal than dehydration), I have never heard of healthy people having adverse reactions.

  3. You know what other cells hold lots of water my beautiful brain not saying I wouldn’t try shorter dry fasts if I thought it might improve a health problem but right now I’ll pass but it would probably be 24-48hr fasts.

  4. The idea that animals retire to a safe place while recovering from illness or injury is a solid one. The question is, if it’s right to assume that the animal internationally stop eating to aid her in recovery. After all, by confining itself, the animal is unable to forage for food and water. What’s overlooked (or not mentioned in what I have read so far) however, is the fact that if an injured animal will continue to roam around instead of hiding while sick, it will make itself an easy target to predators- even if the sick animal happened to be a loin. Humans on the other hand needn’t be concerned about falling victim to predators when sick. Still, I can see why dry fasting is alluring to some and I experienced it in the past, in a religious context no more (: This days, I eat in a small window and I am fine with that.

      1. I think “internationally” was supposed to be Intentionally, lol.

    1. My cat retired to a safe, quiet place and died a horrible death. I wouldn’t take animals isolating and not eating or drinking as health advice.

  5. I was led to believe that there was a connection between insufficient hydration and kidney stones. Many pilots – whose anability to just stop, step out and relieve themselves on long flights leads them to severely restrict their drinking, consider kidney stones an occupational hazard.

    I’m also cautious when it comes to accepting comparisons with animals. Ruminants, with their high-volume digestive system, can take on more water at a single drink than we can, and maintain hydration comfortably over a 24hr period, even in warm climates.

      1. You are right. Humans, however, are the most adaptable creatures on earth.

  6. Hi Mark,
    keep in mind that severe dehydration can cause permanent damage to the kidneys.

    1. Your body goes looking for the water you have loads of, in and around your cells Look up Snake Juice Diet on YT for fasting vids, incl prolonged dry fasting. I think more than 2-3 days dry fasting is nuts but many do it. With correct prep and refeeds. Incl “Kidney Shots” to ensure continued health of the kidneys.
      Now we aren’t animals, Im not a ruminant who can convert mass amts of absorbable calcium from plants, for instance. But animal behavior is highly insightful as they are quite similar to us on some levels.

      1. Hey Fatty! ? I have been really intrigued by Cole and the Snake Diet recently. Mark should do a sit down with him.

        1. Mike, I’ve also been intrigued and amused by Cole and his “Snake Juice”. He takes things a little past the line (actually, a lot) and even talks about an appropriately named “Death Fast” where you not only abstain from water and food, but you “pull” additional water out of your body by going to a sauna and/or exercising.

    2. Dry fasting does not produce dehydration. When the body senses a lack of water it produces its own metabolic water by squeezing hydrogen from your fat cells and together with oxygen you produce water. I personally dryfast 36 hours weekly and am urinating normally for all 36 hours.

  7. A timely article, Mark, especially seeing as Ramadan is right around the corner for me. I’ve always felt in need of your opinion on dry fasting specifically and how it fits into a primal lifestyle, trying to imagine how you yourself would do it!

    I dry fast annually during Ramadan, and sometimes during the year. I’m preparing for a month of 16-17 hr long dry fasts during the spring/summer. It’s more mental than physical to be sure, as it gets easier as one’s body adapts. It’s different this time, however, as I’ve done the keto reset earlier this year and am more metabolically flexible and fat-adapted.

    The challenge for me has been time management with feeding times and exercise. My practice in previous years has been to strength train hard (e.g. bodyweight and kettlebell training) an hour or so before breaking the fast at sunset with water and a moderate-sized meal, rehydrating during the night, and having a pre-dawn meal of mainly fat and protein, with some napping during the day to help stay awake and alert. Fortunately, I haven’t experienced much difficulty managing the above and it seemed to work out well, so it’s admittedly difficult for me to settle for mere walking, but I can appreciate your general advice and rationale from a safety and performance standpoint. I can also personally attest to the many pleasantly surprising benefits it confers which you’ve touched upon.

  8. I also observe the Yom Kippur fast, although I “cheat” and take a dose of Excedrin around 10 in the morning so that I don’t get the hideous caffeine withdrawal headache I did the first year. For me, it is actually easier to fast without water. I hear so many people say that drinking water inhibits hunger, but it’s exactly opposite for me. The water seems to wake up my stomach and remind it that it’s hungry!

  9. This is very interesting! I am always grateful to be exposed to new ideas and information from this blog…
    This makes clear sense to me. And the fact that water is released by fat breakdown is great to have, and explains a lot. This would enable the recovery of severely wounded animals in the wild – which we know can happen.
    I would like to point out that a Ramadan fast involves doing your normal activities while dry fasting – though only between sunrise and sunset. I think that if I try dry fasting, that would be the model I would try.
    And – for those concerned with the kidney stone risk – certainly you would not want to dry fast if that could be an issue for you. But since your body is not processing food during a dry fast, I would suspect that there would be less calcium or other minerals going through your kidneys at the time.

  10. I’ve been keto and fat adapted for awhile, along with IF. Great benefits. So when I learned about dry fasting it piqued my curiosity 🙂

    I’ve now done two 12-hour dry fasts a week apart, 6pm-6am. After the first one, I woke up and my chronic sinus congestion was gone. It’s Spring! Yet I can breathe easily, and am delighting to once again have a functional sense of smell. Hallelujah!

    Now, was it the dry fast or coincidence? I dunno, but the chronic congestion hasn’t returned so I’m happy.

    Also, this week I did like you recommend: broke the fast with water and re-hydrated before my workout. Felt absolutely fine for the hard workout.

    There are some claims that dry fasting is 3x more effective than water fasting, but for now I take them with several grains of salt. (Himalayan Pink Salt, of course 😉 )

    1. This is interesting. I do IF and I close my eating window, generally, by 6:00 and stop drinking any liquids by 7 or 7:30 (not for reasons of dry fasting, but so I can stay sleep all night and not have to wake up to pee). I then drink a cup of black coffee in the a.m. around…7 or 7:30. I just noticed today that I have not been taking my allergy meds – I forgot about them completely – and I am symptom free.

  11. I passed out after not drinking for a few hours in Hawaii. There’s no way I’ll not drink water for a long time on purpose. So many people die every summer in my country from dehydration! (They forgot to drink, or forgot to bring water with them outside).
    Just don’t do it, it will be a very stupid way to die

  12. I have dry fasted at least 6 times. for 24, 36, 48 and 72 hrs. I am a regular water faster and didn’t find it differcult. If you are interested there is a lot of information about the subject on You Tube or go to dryfasting.com.

  13. I do 3-day fasts every couple of months where I only drink minimal water. Once every year I do a 14 day fast where I drink only water. I intermittent fast every day where I don’t drink water for 18 – 19 hours and eat once per day some times maybe 2 meals but that is rare. This is pretty much every day except when I am doing a prolonged fast. I have done many dry fasts where I don’t drink water or eat for over 24 hours and I have never experienced any side effects. I am 47 years old. I have never had a headache in my entire life. I never have had back problems etc. I am fortunate in that regard. I have worked outside in the heat all day without drinking water and sweating a lot and have never suffered from severe thirst etc. The longest dry fast I did was 3 days with no water or food. I was thirsty after that but I never suffered from side effects. The thirst was minor. My body is accustomed to fasting I suppose. I have been intermittent fasting my whole adult life even before I ever heard the term intermittent fasting. Never any problems. As for losing muscle mass, I never have lost noticeable muscle mass. Fat yes but that’s it. Do I recommend this for others? I can’t say that. It’s just the way I have eaten most of my life and it hasn’t been a problem for me.

  14. I think dry fasting is superior to intermittent water fasting as it is easier to do once you get use to it. My longest dry fast was 63 hours, as soon as my lower back ached I broke the fast. I then began doing 1 24 hr dry fast per week and felt like I had plateaued. I now do 23hr Intermittent water fast with 16 hrs of it dry, 5 days a week. The dry fasting has defined my muscles and faded my wrinkles and strech marks. It takes a lot of mental strength going into the dry fast so the almost daily feels more comfortable. I started adding dry fasting into my regular intermittent water fasting 6 months ago and the physically results are astounding, I look 15years younger and my mental clarity and artistic ability have increased to levels I didn’t know existed in me. I recommend dry fasting but not without gathering as much information as possible first. Thank you for your post.

    1. Hi Jennifer. I’m curious as to when you drink your water. Could you provide that information. I’ve water-fasted for 15 days before, am 8 days into a water-fast now, and feel better than ever but have over 100 lbs. to lose so I would like to try your program afterwards as something less extreme. Thanks.

  15. Yet more crap written by people who don’t know a damn thing about dry fasting. I’m dry fasting RIGHT NOW. You don’t even get to “real” dryfasting until you hit the 72 hour mark when your body begins to break down your bodyfat and make metabolic water. 16 HOURS IS THE UPPER LIMIT? I’ve dryfasted 48 hours and walked 5 miles a day with no ill effects. Stop promoting weakass habits in people.

  16. I tied dry fasting the last couple of days. It was maybe a bit cheated, as I had my usual small cup of coffee in the morning. But basically last drank liquids around 8pm, had coffee at 6am and then meal at 4pm, consisting of fatty meat and steamed veggies and a beer (yes, I am a big cheater 😉 ). Otherwise no liquids or food inbetween.

    The observations:
    – Surprisingly I did not feel thirsty as I usually feel during water fast
    – My skin feels nourished and flexible, opposite to feeling of dryness on water fast
    – No constipation, which occurs often on water fast
    – No headaches

    – Little lightheaded but not as bad as on water fast
    – no cold feet. I actually feel my body to be warm inside, even thou the weather chilly (which in itself is a big help)

  17. I have been doing an OMAD dryfast 3-4 times a week for the last 7 months. I basically don’t eat breakfast and lunch on the days I work. I finish my day with 15-20 minutes of ARC indoor climbing. Then I usually follow that with a meal composed of lots of greens, nuts, fruit, kimchee, wine, protein(fish, chicken, beef), sometimes a subway sandwich on top of that, 1-2 chocolate bars and a maybe a glass of water. I’m 5’4″ and my weight dropped from 140 to 130 the first month and has stayed that way since. I think this behavior is health promoting, but I can’t ever truly know.

  18. To be careful. I did my first dry fast four years ago, at 105 hours. That is almost 4.5 days. I did not break it with water slowly. The lighting in my space is quite dark, and I did not see that my hands were slowly starting to dehydrate. I did not venture outside. I did not shower, or brush my teeth, or splash my face with water. At the time as well, the management in my apartment building NEVER turned on the air conditioning, and I would just sweat in my tiny place. I moved my fast out of my loft, and set up a space on the floor down below, where I lay or sat passing time. I tried to do the most research I could, and I thought it would help cysts I had because when I’d water fasted years before, they had become smaller, cellulite disappeared, and I cannot even remember all of my benefits, sorry, but I’d say not as many as I’ve gotten when juicing. Juicing for me has worked wonderfully. Anyhow, the symptoms that you need to watch out for when dry fasting, CAN BE CONFUSED with the positive symptoms. I would say not to dry fast by yourself without someone checking all of your vitals, and even IF you had someone that had experience in it with patients over years – to remember, that EXPERIENCE doesn’t mean they know any better than you. Moving on, my eyes became red, I had dry hands on the outside without realizing it until I got outside into the natural sun light. My tongue got heavy, and felt needle like, it began to do this on and off around the end of day 3. I had a pressuring in my pelvis. In my chest though it was not pain, but I did start to have a rapidness in my chest, by than I was so caught up in it, that I thought what harm could another 1-2 hours do. I had some light aches, and pains all over, just like in a water fasting state. I was hopeful to heal many internal issue’s, and I was hopeful to heal the damage done when I’d abused the water fasting. I made things worse.

    I’ve dealt with severe hair loss since not breaking it correctly, as I was SEVERELY dehydrated. The only way to stop the hair loss, all over my body, my head, and to the point it started causing severe itching, and a burning like sensation (even with redness) is to drink copious amounts of water a day. Oddly, the hair continued to grow, and fall, and at first I thought I had “TOXIC BUILD UP” – NOT. I tried to get in touch with the Doctor you mention here, to no avail. I did get in touch with the South African Doctor who is also a big name in the Dry Fasting community – I don’t have those notes any longer. He basically said to me, that, he never recommends just anyone dry fasting, and that I should make a post about my issue’s on his forum with my issue’s, and MAYBE someone could help that studies it in their practice. The hair loss isn’t the only damage done – once I felt not so ashamed and intimidated to ask and get help from Doctor’s, and the like, I was told by my now GP, that I was close to having a heart attack at only 30 years old – in fairly good health before. For awhile I dealt with chest pain and heart pain, that felt like it would squeeze after any type of activity, – especially cycling – as I did that as a way of transportation in my city, and I can keep up wit the traffic…. that has gone, yet every once in awhile, I get the minor chest pain. The pressure I had in my pelvis, well, it led me to having a numb left leg or left arm a week before my menses for about 1.5 years. It also added a very strong nausea at the same time leading up to my menses, in which this has just started to cease in the last 8 months. These things NEVER happened before, so I have no idea on the damage I did, or IF there was something else going on within, that dry fasting brought up. No idea. I think it is clear to say, I’ve unbalanced myself. I also began all at the same time, to have a VERY HEAVY MENSES, and a VERY PAINFUL one at that. I was hoping to heal a full back injury, a torn muscle, the pilar cysts I’d mentioned. A few other issue’s. I was a very healthy person, before I started experimenting with a Raw Vegan 811 / 955 diet, Water Fasting, Dry Fasting. Yes, the body IS resilient, but I interestingly enough, have very good genetics. Up until last year, people still thought I was 18-23. I have always looked very young, I never did damaging things to my mind, or body in my teenage years, but I have now done a terrible amount of damage that is likely permanent in my mid twenties to early thirties due to thinking I had enough information on the web, and being in unhealthy states of mind and took my health into my own hands. I REALLY CAUTION PEOPLE on fasting. If you don’t understand what you’re doing. DON”T DO IT.

    I have permanent kidney damage from the water fasts I abused 9 years ago. I got stuck in the starve / binge cycle, and I’d break 10 to 20 days water fasts on a liter of vodka. Eventually it led me to having swelling feet, and legs, and I didn’t know what was going on than, and I felt I couldn’t tell anyone, as I was on the poverty line, receiving an income from the government and dealing with severe mental health issues. Yes, mine is an EXTREME Case, but it is a caution. I still deal with the ramifications of my actions 9 years ago. I have edema in my brain, most days upon waking, it feels like the worst Depression of my life, until I get up, and I guess it flushes out, or runs down internally. 9 years ago, it would take months than to weeks, than to days to completely disappear. I left the all raw vegan diet, mainly on fruit, because the fruit was causing the edema to be worse. My guess is that the dry fasting that gave me severe nausea was also caused from the kidney damage I’d done years previously, and it just exasperated it. About 8 months later, after the dry fast, I started to have severe brain fog, and fell very ill, muscle strength loss, chronic fatigue, it all just hit me one day out of the blue. I was only working 30 hour work weeks, and BAM, had to sleep at 4pm, and would sleep until 12am, get up eat and drink, because I missed dinner…and than back to sleep until 6am, where I felt I needed more sleep, the illness, if you want to call it that, lasted 2.5 years, and it became worse. I was tested for Fibromyalgia, I thought maybe it was Cancer, the inflammation I caused in my body is so severe that two years ago, I was tested by a machine that showed that I had LYME DISEASE because the amount of inflammation matched that of someone with the illness.

    People thought I was exaggerating, or trolling, or putting down their efforts to heal dis-eases, and that they’d had wonderful experiences. I am not, I wasn’t. If you don’t know, don’t do it. You can hurt yourself.

    I too have healed, cavities, hair, skin, old scars, internal injuries through a Raw Vegan diet, a cooked Vegan diet, an omnivore diet, a pescatarian diet, and juicing.

    Most people won’t go to the Extreme’s that I have, but some will, because some are out there with the same illness as I still have, because I’ve talked with them online. I still beat myself up every day for the body I had before bleaching, water and dry fasting.

    People that are GURU’S and Health Advocates, I don’t care if they’ve written and published books, have abs and look healthy, can stand on their head and spin, have a PH D frame on their wall, make a ton of money, if they’re not kind truthful, considerate and BALANCED folk – BE CAREFUL. Listen to your gut instincts. Do your research, get both sides of the coin. Make certain you’re in a healthy mind state.

    Be Careful of what you read online.

    I also had pressure in my abdomen, and had what felt like a ball that would poke out from time to time, really an odd feeling. I’ve now been to naturopaths, Doctor’s, Psychiatrists, Psychologists, healers, ect ect and from what I can tell is if they practice a certain way, all of a sudden you have what they practice. But I know what I did to myself it is irreversible, and although it has gotten better over time, I know it will never be the same. I feel at times, I have actually sped up my aging internally, to externally because of what I did. I could have lived a longer life.

    Hydration is key. A diet that works for YOUR body. Exercise. A proper sleep schedule. Finding enjoyment in your life. Not for others.


    1. Anyone who breaks a 10 to 20 day fast with a liter of vodka is mentally ill. You shouldn’t blame fasting for your results. People fast for the health benefits.I would advise you to never fast.You are giving it a bad name.

  19. Hi. I would like to tell you about my dry fast experience. I broke my fibula ( with two fractures). After the first week I was put in a walking boot and decided to do two 24 hour dry fast a week. After a month in the boot the doctor cleared me and said I didn’t need to come back. I am an overweight post menopausal woman. I read that a broken fibula takes a minimum of 3 months to heal ( up to 6 months). I was walking around with minimal discomfort in 5 weeks. Dry fasting works.

  20. Jain Religion in India has been practising dry fasting for ages. This is not new and Jain people have been doing it for 1 to 16 days

  21. Mark, if you IF already, you have to try a 24-36 hr dry fast. Hunger is absolutely NONexistent. It’s so incredibly different from a water & electrolytes extended fast. I’m going to dry fast 36-48hrs weekly now instead of 3 day water fasts! I do brush my teeth just before starting at 7pm and once more —and also wash my hands off as needed though.!

    1. yes I also am aiming to do this on a weekly basis, thought of doing every other day dry fast, what do you thing to that?

  22. I dry fast 36 hours every week.I also do another24 hour water fast and two days of 16-8 intermittent fasts..The dry fast is not really difficult as i find myself neither exceptionally hungry or thirsty at the end of 36 hours. A big thing i like about the 36 hour fast is that your enjoyment of food once you start eating is through the roof.

  23. I’m currently 36 hours into my first dry fast. I’m taking it really easy, staying indoors and not exerting myself at all. I feel absolutely fine and I do feel cleansed from the inside out in some way. I don’t feel thirsty or hungry.

  24. Your article was spot on and informing.

    For the last two months or so I have intermittently carried out a soft water(max of three days) and dry fasting(up to periods of 36hrs at a time).

    I have lost 8kg, feel slimmer and feel more energetic. I am going to continue this new found tool to become more healthier and shed some tummy fat.

    I have not felt any side effects and feel well to continue, I am monitoring my self to make sure I do not end up with long term damage.

    Thanks for your inspiration in health matters and look forward to hearing from you.

    All the best

  25. Here’s a little something constructive for a change.

    I dry fast. Have been for years. It’s not an uncommon practice for eastern Europeans. I do it for health and weight loss. It is common for me to do a protocol that involves 88/8 or 110/10. Some people start with 22/2 then build up to 44/4, 66/6 up to 88/8. 110/10 is very rare but some of us do it.

    Here’s the spiel. The larger number represents air only time in hours. The smaller number represents time for hyper-hydration and feeding.

    The protocol is not dangerous. Peoples’ stupidity is what is dangerous. The problem with dry fasting is that people go into it without adequately pre-hydrating and without being in ketosis. For the process to be safe these two things need to happen.

    I really don’t like when people have an opinion based on nothing meaningful and especially if they haven’t done it or haven’t explored the subject with people who are routinely doing it. (Saying this because of opinionated comments..)

    When you downtegulate aldosterone (by drinking copious amounts of water) and mTor, and upregulate AMPK, dry fasting becomes relatively easy. That is if you’re mentally and emotionally a stable person. If you’re a whiner you’ll find every excuse you can think of to convince yourself otherwise.

    Also, I observed no meaningful muscle loss as witnessed by my dexa scans. I just wish I did them more frequently and at more accurate times. Cole Robinson proved that dexa scan shows water as lean mass which makes those results garbage worthy. So depending on your hydration level you’ll show more or less lean muscle. In essence you’d have to take a dexa while completely dry for the same amount of time, every time, to get consistent results.

    In addition, I exercise while dry fasting. Nothing excessive. Some hight intensity sprints and some steady sate cardio. Some boys weight excercises including squats and some stretching. It makes you a bit thirsty initially but you power through it and you’re fine later.

    Some people take up a “loser” version of the fast period where you’re allowed to consume 1 oz of non caloric liquid up to 4 times a day with some shilajit in it. Some people drink a 1oz espresso some water. It also upregulates AMPK. This makes dry fasting a wee bit easier. I mostly go hard core dry.

    Breaking the fast involves drinking water with sodium bicarbonate first. Then water with lemon. Then lots of water.

    Anyway… look up 88/8 from interstellar… he assembled over 1000 study list of what and why.

    I’m also planning on writing up some information and publishing eventually.

    1. I’ve seen this advice once or twice before to break the fast with sodium bicarbonate. Why? Can you provide a link that explains the benefits?

      Also, drinking water with the juice of a lemon smacks of “ritual” moreso than necessity. The acid from the fruit will interact with the bicarbonate. For example, assuming ascorbic acid (vitamin c) from the fruit, you’ll make sodium ascorbate in your stomach if you drink them back-to-back (they produce a gas too… fizz!).

      I’ll try looking up this interstellar guy.

    2. I checked out Interstellar and his 22/2, 44/4, 66/6, and 88/8 approach to dry fasting. Y’all can find his website easily by entering “interstellar 88/8” into any search engine.

      Anyway, I’d be very cautious following this guy’s recommendations. He has a pretty comprehensive page that links to a lot of the current research on dry fasting as well as research on related topics.

      However, his dry fasting advice is ridiculous. He suggests drinking (!) an espresso with his special combination of herbs on a regular basis during the dry fast. Uh, what? Drinking liquid during a dry fast is pretty much the opposite of dry fasting. Yes, the amounts are small, but do you think it’s a good idea to drink a diuretic when you are avoiding drinking new fluids? Sounds like a recipe for dehydration or other complication.

      Anyway, buyer beware.

  26. I have tried dry fasting and I’m not always sure if it helps with fat loss or anything else. I’ve done it for 24 hours and 16 hours and one time 36 hours. I’ve gotten headaches sometimes and sometimes I don’t. I am going to keep trying though. I’ll keep you informed.

  27. I’m in the middle of a strict dry fast right now, going on 68 hours. My plan is to break my dry fast tonight and continue fasting for an additional period. I didn’t start this dry fast with a number in mind, but I think it’s best that I end it at 72 hours for safety reasons.

    I feel absolutely fabulous! Granted, I’m used to fasting and am “fat adapted” so fasting is a normal part of my routine. This is my second attempt at dry fasting. The first dry fast only lasted about 36 hours.

    I have had zero hunger in my three days, which has made it easier than regular fasting, in my experience. I also did 30 minutes of cardio yesterday to break a sweat and pull more water out. At the end of the day yesterday, I could feel my body hurting from lack of water, but during my sleep I fully recovered without any thirst this morning. I feel great! I also tested my blood ketones and glucose level this morning with my precision Xtra. Ketones were 2.5 mmol/L and blood glucose was 53 mg/dL which is on the low side, but not too low for me. I also monitor my sleep with the ?ura ring and my sleep has been great throughout, although my readiness score was low today due to elevated resting heart rate. Normally, I’m at about 50 bpm, but last night i bottomed out at 58. I attribute that to the extra work my body was doing to recover from the 30 minutes of hard-ish cardio where I burned 500 calories.

    Above all else, I’m listening to my body and monitoring for any signs that something is wrong.

    My motivations for this dry fast were accelerated autophagy, healing benefits, weight loss and curiosity. So far, this experience has exceeded my expectations, although I can’t really measure autophagy. I have stage IV Melanoma so I’m fighting this F-ing cancer with everything in my tool box.

    1. Good for you! On the fighting, I mean. Do not under-estimate the power of meditation or turmeric.

      Also, you might want to look into Dr. McDougall’s advice, if you haven’t already.

      I hope for your success. I will pray for you.

  28. Good research. You can not talk about it if you have not tried it though?

    I do it for 24 hours today it enda at 18:00.

    It feels great.

  29. I believe discomfort is fine on any fasting regimen- that’s the point isn’t it? No dry fast feels comfortable- push past it- that’s where the healing starts.

  30. It was one of the best experiences I have had I did a 10day water fast and the 10th day I made a dry fast. I felt very good and mentally clear

  31. I do a dry fast of 20-24 hours 3-4 times a week. Been doing so for 1.5 years. I don’t lose weight. I still pee clearly though not a ton. I donate blood 6 times a year and they check the bloodwork, so I haven’t been notified about anything abnormal. When I eat my OMAD, it’s mainly food, maybe a glass of wine, maybe a glass of water, but no more than that. On my days off I’ll go mountain biking dryfasted. I’ll bring water, but rarely will I drink it.

    There are three ways that you can boost your metabolism to waste energy(fat).
    1. Be keto adapted. If you make ketones, this gives you redundant and excess energy that often times you may not even use. If you pee of ketones, you are literally peeing off energy.

    2. Optimize brown fat. You can do this from exercise and cold. You expose yourself to enough both, and you get upregulation of the membrane transport protein thermogenin(or UCP uncoupling protein) of the mitochondria. This essentially creates extra flux of H+ from the mitochondrial intermembrane space to the matrix to create heat. You literally are burning calories to make heat by just by idling.
    3. Finally if you’re dry fasting regularly, the body will sense an H20 deficit. Your body will upregulate electron transport proteins in the mitochondria. It has to, you need water or you’ll die. The processing of acetyl-CoA through the electron transport system in the mitochondria produces metabolic water that can sustain you.

    Occasionally I’ll drink water, but the one thing I notice is when I do, I get the same dopamine rush that I get when I eat sugar. It’s interesting.

  32. Great read – thanks

    I have done a 5 day HARD dry fast. During the 5 days I was still able to go and volunteer at a homeless shelter as it was during Christmas time. I have done several 3 day dry fasts in the past & eat a raw vegan diet as well as drink 4 litres of water daily so the 5 days wasn’t hard for me. Just the dry mouth was annoying as I had to talk throughout the 6 hour shift at the shelter where I was volunteering. Slept with windows open and found the cold winter air very hydrating. I also bottled some of my urine and the fat deposits were evident at the bottom of the bottle. Energy levels varied throughout but generally felt fine. would do it again if I had to but would recommend to people on SAD diets – it’s definitely dangerous as the organs might become overwhelmed with toxicity

    1. Fat deposits at the bottom? Fat floats. Always. Probably some sort of sediment from your unnatural diet.

  33. Hi. I’m Victoria
    I have been doing dry fasting during the night for 14 hours generally. While on holidays I could not do it for 4 days. Otherwise I have done it for about 5 weeks now. I aim for 14 hours but at least 12.
    I think I may have put on weight but remain the same size.
    I was hoping to lose some weight.
    I read somewhere you will see results after 10 weeks or so.
    I try to do it peanently. I like it.

    1. I have personally found that when I dry fast, I tend to build muscle more than lose fat.

      The only times I lost fat while fasting was when I had done intermittent fasting for a long time and then dropped into an absolute water fast. Or, when I just did extended (24 – 48 hours) intermittent fasting. Both times I had carbs.

      I also found that following some basic advice from Dr. McDougall to really focus on low fat, low salt, high starch, I had the same basic results as mostly eating keto and doing extended intermittent fasting, as far as losing water and I had better results in losing fat.

      There has been one study done that proved increasing starches /carbs can actually increase your metabolism, even if you are eating lesser calories. And, one study that seemed to prove the same thing in that they took groups of young men and had them eat 12 slices of bread in addition to their regular meals and while they were eating the extra bread they were losing weight.

      There is a video on YouTube by a lady who talks about how due to her dad’s health she and he both started increasing their starch intake, even though still eating animal products, and they lost weight and got much healthier. But, that this became even truer when they cut out all meat, fish, fowl and dairy.

      I also lost a bunch of weight and went through a very transformative experience when I inadvertently found myself in a situation where I was eating almost only non-starchy vegetables for a few days and then a few more days of eating exclusively non-starchy vegetables.

      Not just weight loss. I could move super fast and the heat didn’t affect me, except that I was sweating (which is something I do poorly, most of the time, no matter how hot it is). I didn’t get a sun burn, I never felt overheated. I was running purely on fat fuel. And, I felt amazing! Then, I started detoxing fast and hard and that scared me because I had no idea what was going on and I was not prepared for it.

      There are so many things to try. And, it is okay to do one for a while and then switch. In fact, it is, according to some doctors, the best method so that your body doesn’t have a chance to kick into homeostasis.

  34. I can honestly say that I, as a person with many health issues (apparently, all stemming from Crohn’s and a LOT of stress) went on a 60 hour dry fast in the summertime in Southern Arizona, which culminated in about a 2 mile walk in about 115 degree weather, with the hot sun burning down on me, and, then I took a drink and only when I took a drink, a small one, out of extra worry due to all the warnings people give about dry fasting, did I begin to have any feeling of thirst or any other “bad” feeling.. I probably should have waited until I cooled down and actually bundled myself up as much as possible due to air conditioning. The hot weather was no problem for me and I never felt thirsty. The small drink of water and over-generous air conditioning was terrible.

  35. Also, on the thing about animals sometimes not drinking water or eating food due to how ill or injured they are:

    Kudos to you for admitting that you don’t know something. However, points loss for lack of research.

    It is true. I know that because I grew up around animals both wild and domesticated, and some that were in-between. I’ve seen some that were that badly injured or ill and I’ve seen how they recover, and I’ve seen how sometimes humans cause them problems because the animals love them and want to make them happy so they actually drink sooner than they care to and they don’t heal as well or recover as quickly as the ones who are left alone or who are more adamant.

    If you don’t know it, you can find out by asking those that do. I don’t mean me. Someone more official sounding – people who work at zoos, who study animal life, who run nature preserves, old episodes and issues of National Geographic, etc.

    I’m afraid you might dissuade people who would take your “I don’t know” as a polite way of saying, “I can’t prove it is wrong, but I am sure it is.” When, in point of fact, it is true that animals both dry fast and wet fast.

  36. The 5 people in the study were not dry fasting for 4 days, that could be deadly in most cases. They faster normally, that is eating nothing but drank water. This is a direct quote from the paper:

    “subjects continued with their usual activities but nothing was taken by mouth but water”

  37. I’ve done a 3-day dry fast on multiple occasions. As I type, I’m on hour 40 of a 2 day dry fast. My experience is that it’s actually easier in some ways than water fasting. I experience zero (with a capital ‘Z’) hunger. I don’t even feel that thirsty for the first day – although this was hard won after several dry fasts.

    My experience is that I generally oscillate between feeling pretty calm (even euphoric) and thirsty, to feeling like I have the flu and not thirsty at all. I take those flu-episodes to mean that my body is cleaning up something and that I should let it takes its course.

    My belief (based on no actual science, just conjecture), is that dry fasting is perfectly safe and healthy in moderate doses. I think most healthy people could probably work up to 3 day dry fasts without serious issues. This is especially true if your mindful of other things that you will be more vulnerable to like heat stroke, overexhaustion from exercise, etc.

    Also, always break the fast with water and a bit of sea salt! if you have some natural calm (magnesium supplement), throw some in as well. Give a couple hours for your body to assimilate the water and electrolytes before eating food. The first food you eat should be low glycemic index foods (meat and veggies). You should keep it Paleo for the first few meals back. Don’t break your fast with wine and chocolate – you can die – be smart!

  38. I eat omad and sometimes forget to drink anything so have accidently dry fasted for 23 hrs here and there.