Why Dry Fasting?

Unspeakable among most medical professionals, dry fasting is gaining an almost cult-like popularity: most of the grassroots information about it is steeped in superstition and it is rife with uncritical repetition of rules, the only justification of which is along the lines of "That's what the Leader has proclaimed."

I'm in a funny position here; the Carnivore Diet is often criticised for the same kinds of reasons: those in the know <cough> ask you to take their word for it, saying that you can't predict from prior knowledge of a superficially similar regimen what will happen if you do the protocol exactly as prescribed. Rest assured this irony has not escaped me.

While dry fasting might sound crazy, I'm going to tell why I think it's probably actually good. I'm also going to point out more parallels between the relationship of dry fasting to fasting and the Carnivore Diet to low carb diets.

I can't do it all justice in a single post, but consider this an introduction. And I don't normally feel I have to say this, but like everything I write, act upon it at your own risk.

Contents
When fasting fails, it fails badly
How did I get interested in dry fasting?
Dry Fasting for Fat Loss
Fluid restriction shouldn't matter, because calories, right?
Fluid Restriction vs Dry Fasting
Edge Cases
Filonov's water fasting is fluid restricted!
Mass Restriction
You can't gain mass you don't ingest
Electrolytes
References

When fasting fails, it fails badly

Even though I used to fast with ease, I've had some bad experiences with fasting in the more recent, post-infectious past.

Specifically, in those cases, I was drinking broth and water, did not lose weight even at the end of ten days, my ketosis didn't significantly go up, and I felt terrible the entire time -- cold and exhausted. Forcing extended fasts, which I did twice, seems to have also hastened menopause for me, as both times were followed by my only experiences of amenorrhea outside of pregnancy, and the second time my period never came back. Obviously, at my age, it was "about to happen anyway", but the timing and other symptoms lead me to believe the process was accelerated by inability to access or use my ample fat stores.

This makes perfect sense in light of the satiety vs restriction model of fat loss I described in a recent post. It also prompted me to write a talk for the Low Carb Cruise last year on the perils of fasting when your body is in a fat-metabolism resistant state (for whatever reason). I called it Not so Fast! There was a recording which I'll link below, with the disclaimer that I accidentally left off some important information and feel it needs a do-over.

However, I stand by the concerns I raised about fasting and protein restriction, even though I acknowledge that many people are doing well either with total fasting, or with protein restriction (sometimes ketogenic, and sometimes not). Given that some people have died with poorly constructed PSMFs, we shouldn't be too cavalier.

Not so fast!

How did I get interested in dry fasting?

Although water/broth fasting hadn't been going well for me, I've been fascinated with dry fasting for several years.

My interests were initially piqued some years ago when I came across a study in finches showing that an overnight fast without water results in six times the weight loss as an overnight fast with water. I mentioned this study in my "salt talk". Here's an excerpt describing it:

(4 minute excerpt on metabolic water)

This is astonishing, at least to me!

I also connected it with statements from Cahill about fasting requiring almost no water because of metabolic water and changes in fluid dynamics. These latter two insights became part of my understanding of why adding salt to ketogenic, and especially carnivore diets is likely to be misguided.

"Because of the small excretion of urea (normally the major osmotic solute), there is little need for obligatory water excretion, and urine volume may fall to 200 ml per day. Thus a fasting man need drink very little water, the water produced by metabolism approximating that lost in urine and that lost by evaporation from skin and lungs." -- George Cahill

I had already tried dry fasting back before I gave the above talk. I had even downloaded a copy of the book by Dr. Filonov, one of the two people considered experts, in the original Russian. Unfortunately, my Russian is not quite good enough to read it a confortable pace and I didn't get very far (but see below!).

When I tried it then, it was a short encounter. About 36 hours into my first dry fast, a kidney stone started passing, and so of course, I immediately started drinking again. After about 30 excruciating minutes, the stone passed, along with my interest in trying it again, which didn't return for some time. However, my curiosity couldn't be tamed and I eventually came back to it.

(Note that I don't and did not at the time think that the dry fasting caused my kidney stone to form--it was known to be pre-existing, I think it caused it to shed. It was just punishing and I didn't want to repeat it soon.)

Dry Fasting for Fat Loss

One of the tenets of the Dry Fasting Faction is that it's not primarily a fat loss strategy, it's a healing protocol. This is directly parallel to the Carnivore Diet origins. When we were a small group of people experimenting with the unthinkable idea of not eating vegetables, the primary forum for discussion was called "Zeroing in on Health", not "Zeroing in on Weight Loss". Fat loss was a very common (though not universal) side-effect, eclipsed by the other benefits. It felt like a bait and switch. We went there to figure out how to better lose weight, and ended up off our inhalers and antidepressants. In the same spirit, when Shawn Baker started his Carnivore groups, the slogan was not "Meat Makes You Thin!", but "Meat Heals!"

Nonetheless, almost everyone, myself included, finds these protocols because they want to lose fat, so I'm going to start with that.

Fluid restriction shouldn't matter, because calories, right?

If you think that the major contributing factor to fat loss is caloric intake, then dry fasting for fat loss will make no sense whatsoever. Not only does it make no sense from that perspective, but it is considered unnecessarily risky. Although fasting has gained wide acceptance in the past 10 years or so, dry fasting is still quite taboo. For example, it is against the rules of the primary fasting groups on each of Reddit and Facebook to discuss it, period.

However, the above two points suggest that it is no less safe than water fasting, at least in short-term fasts: Cahill's point that very little water is needed during fasting, as well as the very intriguing finch study suggesting that fat oxidation is actually accelerated when water isn't provided. If this applies to humans--and I don't see why it wouldn't, even if the factor of acceleration differs--then drinking during fasting slows down fat loss.

The main healing effects of dry fasting have been attributed to autophagy, and there is a direct relationship between depth of fat oxidation, ketosis, and autophagy [1]. So if that attribution is correct, the healing effects of dry fasting would also be directly related to its fat loss enhancement.

Fluid Restriction vs Dry Fasting

Here is where I'm going to veer into blasphemy territory.

In the Dry Fasting Lore, the avoidance of water is so sacred that there is a even a distinction between a "soft dry fast" and a "hard dry fast" where the only difference is whether you let your skin come into contact with water, such as with bathing or tooth brushing. Most people I encounter don't make a big fuss over this. However, on the contrary, most people I encounter would draw a firm line between no fluid intake and a very small amount of fluid intake. To almost everyone in dry fasting circles, a sip of water (obviously!) breaks a dry fast, and puts you firmly back into the realm of water fasting.

Even though I am an adamant stickler that an avocado on your plate firmly moves you from a Carnivore Diet to a low carb diet, even if everything else you ate that day was meat, it seems to me that the water situation is different in a particular way. This may seem hypocritical, so I'm going to explain further with caveats.

First I'm going to tell you why I think so, and then I'm going to reiterate that my experience with dry fasting is limited, and that I think you have to respect the folks on the ground if they say their experience is different! And then I'm going to give an important example of water restriction as therapeutic.

Edge Cases

Often we find extreme effects near the boundaries that are not present closer to the middle where changes might appear more linear.

Lack of understanding, deliberate or not, about how low carbohydrate intake has to be to induce a ketogenic metabolism, is why, for example, we get disingenuous-seeming epidemiological studies about "low carb diets" such as the one colleagues and I criticised in "Re-evaluating low-carbohydrate diets and mortality" [2].

Even in a case like the Carnivore Diet, there is likely to be an amount of plant intake that is too small to prevent the benefits, and this is likely to vary by individual, by the type of plant in question, and the frequency of ingestion. What can be said with more certainty is that there is some level of plant intake that is too high for the majority of people who notice benefit on Carnivore to get it, and that when that benefit occurs it is qualitatively different from a mere low carb diet.

Similarly, I find it implausible that there would not also be a small buffer of water intake that simply cannot disrupt the benefits of dry fasting compared to water fasting. What seems most likely to me is that any amount of fluid intake that is less than water requirements while ketogenic is going to stimulate extra fat oxidation. At the very least, there is likely to be a spectrum of added benefit when fluid intake ranges from nothing to somewhere below requirements.

Further, water is an endogenous compound. The best explanation I know of for how eliminating plant intake could have health benefits is that xenobiotic compounds in plants induce an immune response. I went into this aspect of Carnivore diets in a talk called “Meat is Food, Plants are Medicine” for Low Carb USA 2021. The talk is hosted on the Keto-mojo website. Here is a slide from that talk classifying possible ingested substances depending on whether they are also made in the body, and whether they are used for something or just eliminated.

Water is decisively an endogenous substance, and therefore, unlike, say, sulforaphane, will not only not cause an immune response, but other than its detection on the way in, its origin cannot be distinguished.

Nonethless, I would tend to believe anyone who told me he had drastically different results between fully dry fasting and mere water restricted fasting. What most people actually compare is dry fasting and water fasting to thirst or beyond. But I'm open to hearing otherwise.

Filonov's water fasting is fluid restricted!

People often note that Dr. Filonov sometimes suggests a short period of dry fasting followed by water fasting, but few seem to realise that he means fluid restricted water fasting.

In the chapter "Types of dry therapeutic fasting and their differences", he writes (translation aided by Perplexity; original Russian below [3]:

Combined fasting

Combined fasting is typically applied as follows: 2-3 days of dry fasting, then water is allowed.

Comment:

Advantage: Combined fasting provides a greater health-improving effect than complete fasting (with water), as by the third day of absolute fasting, a ketoacidotic crisis occurs, after which the patient's well-being significantly improves, and the greatest therapeutic effect for the body is observed. With water fasting, the crisis occurs only after 7-16 days. In this method, for 1-3 days (depending on individual tolerance), patients are asked to abstain from food and water, and cleansing enemas are not prescribed. Starting from the 2nd-4th day, patients resume water intake, limiting it to 10-12 mg/kg of body weight per day throughout the fasting period, and continue complete fasting according to the usual FDT (fasting diet therapy) method.

(Emphasis mine. I don't fully understand what his famous "acidotic crises" refer to, but the first one is likely a variation of keto-adaptation.)

EDIT: the following paragraph was based on the assumption that this was supposed to say 10-12 mL/kg, not mg. I can't make sense of mg here, and I'm in the process of looking for clarification. Thank you to Darius Bacon for pointing this out.

This typically would work out to somewhere around 0.5-1.0 kg, or half a litre to a litre of water, and besides fluid restriction, this is also a form of mass restriction.

Mass Restriction

Mass restriction has been advocated by others before.

Cole Robinson, the drill sergeant fasting guru of Snake Diet fame, once described a protocol he called "death fasting" in which he advocated alternating dry fasting with drinking and eating whatever you like, as long as its total weight is no more than a quarter of what you lost in the previous day's dry fast.

More generally, there was a paper a couple years ago by Anssi Manninen arguing that calories in, calories out (CICO) is meaningless because "Body mass can only change as a result of net mass flow; thus, the only food property that can augment body mass is its nutrient mass, not its energy content." [4]

Dr. Michael Eades, always on the leading edge, presented this idea more informally last year at Low Carb USA:

Dr. Michael Eades - 'Weight Loss: Calories, Insulin, or a Third Alternative?'

The coincidental (or not) result is that fat is the "lightest" source of calories, so a diet of primarily fat should be the best for weight loss. Who knew?

You can't gain mass you don't ingest

While restricting mass doesn't guarantee weight loss, one thing seems tautological: unless you are a plant, converting atmospheric carbon into body parts, you can't possibly add more mass than you ingest . Moreover, daily metabolic processes entail obligate mass losses. Therefore, if you water fast, you can maintain or even gain weight, but if you dry fast or restrict fluid and mass, you can enforce a limit on regain.

The fascinating thing is that within a given mass, you can choose to ingest from within a tremendous range of possible calories. For example, if you restrict mass intake to 500g, and compose it of only fat (no water), you can eat enough substrate for ~4500 kcal. If your obligate losses stay true to 500g, then you would not gain an ounce. More practically, if you start with 3 days of dry fasting, and lose a typical 3kg, and then follow this with 1kg of combined fluid and other mass restriction, you can limit or even prevent the assumed-necessary regain.

This is what Filonov is doing with "combined fasting", and this is exactly what my own recent experiments have shown:

Over the past three months I have lost 20lb, 15 of which was in a single month during which I followed 1-2 days of dry fasting weekly with several days of fluid restricted fasting or mass restriction, before returning to ad libitum eating. Weeks when I tried dry fasting followed immediately by liberal water fasts resulted in complete regain.

Moreover, the mass limit I had to enforce to prevent regain fell within Filonov's 10-12mg/kg range.

Electrolytes

This post is too long already, but I'll mention one more way in which dry fasting compared to water fasting is comparable to Carnivore compared to Low Carb: the common wisdom in both the keto and the fasting worlds is that supplemental electrolytes are essential. Carnivore and Dry Fasting share the cultural tenet that electrolytes, including salt, are not needed and can create imbalances. If you're unfamiliar with this old and somewhat lost Carnivore knowledge, please see my talk from AHS 2022:

Blood, Sweat and Tears: how much salt do we really need?


References

1 See eg. Mattson, Mark P., Keelin Moehl, Nathaniel Ghena, Maggie Schmaedick, and Aiwu Cheng. “Intermittent Metabolic Switching, Neuroplasticity and Brain Health.” Nature Reviews Neuroscience 19, no. 2 (January 11, 2018): 63–80. https://doi.org/10.1038/nrn.2017.156.

2 Feinman, Richard D, Katharina Lechner, Eugene J Fine, Jennifer Elliott, Maeve Thompson-Starkey, L Amber O’Hearn, and Nicolai Worm. “Re-Evaluating Low-Carbohydrate Diets and Mortality.” The Lancet Public Health 7, no. 7 (July 2022): e581. https://doi.org/10.1016/S2468-2667(22)00118-9.

3 Сергей Иванович Филонов
Сухое лечебное голодание - мифы и реальность/ С.И. Филонов - Барнаул :
Изд-во ООО «Пять плюс», 2008, - 336 с.

ISBN 978-5-9900731-7-3

Комбинированное голодание
Обычно применяют комбинированное голодание: 2-3 дня сухого,
потом дают воду.

Комментарий.
Преимущество. Комбинированное голодание дает больший оздоровительный эффект, чем полное голодание (с водой), т. к. уже на третьи сутки абсолютного голодания наступает кетоацидотический криз, после которого самочувствие пациента значительно улучшается, и наблюдается наибольший лечебный эффект для организма. При голодании с водой криз наступает только после 7-16 дней. При данной методике в течение 1-3 суток (по индивидуальной переносимости) пациентам предлагается воздерживаться от приема пищи и воды, очистительные клизмы не назначаются. Начиная со 2-4-х суток пациенты возобновляют прием воды, ограничивая его до 10-12 мг/кг массы тела в сутки в течение всего разгрузочного периода, и продолжают полное голодание по обычной методике РДТ.

4 Manninen, Anssi H. “Chronic Positive Mass Balance Is the Actual Etiology of Obesity: A Living Review.” Global Translational Medicine 2, no. 1 (March 1, 2023): 222. https://doi.org/10.36922/gtm.222.

Footnote. A reader on X suggested that fatty acids can add mass via added oxygen.