Dry Fasting. Is there any science to this?

(Bahram Ka) #41

I looked into some of his specific claims. Even if dry fasting is legit, the evidence and references its proponents cite are often twisted or based on pure conjecture and unreasonable extrapolation of basic physiological fatcs.

“When we fast our body creates water primarily as a byproduct of the fat we are burning. Hydrogen released from the metabolized fat combines with oxygen from air and creates h2o"
Estimated that every day the body is able to produce a liter of metabolized water in this way, and freshly synthesized water is believed to be much more pure than water consumed from the outside because it is free of toxins found in water we drink”

  • 110 grams (=mL) of water is released for 100g of Fat, so you would need to burn 1000g of fat, or 7600kCal for 1L of water, which we know does not happen.
    From “Dietary Reference Intakes for Water, Potassium, Sodium, Chloride, and Sulfate”, MN Sawka - 2005 - dtic.mil;
    "… water production is an average of approximately 250 to 350 (m)L/day for sedentary persons—but which can increase to 500 to 600 mL/ day for physically active persons (Hoyt and Honig, 1996). Hence, respiratory water losses are roughly equivalent to, or offset by, metabolic water production (Table 4-2; Hoyt and Honig, 1996)"
    and from: National Research Council. 2003. “Nutrient Requirements of Nonhuman Primates”: Second Revised Edition. Washington, DC: The National Academies Press. https://doi.org/10.17226/9826.

“… The gross yield of metabolic water from oxidation of 100 g of carbohydrate, protein, and fat is about 60, 41, and 107 g, respectively (Askew, 1996). However, excretion of the urea produced during protein oxidation requires nearly all the metabolic water released. Thus, there is no net water yield from oxidation of protein. Metabolic water furnishes about 8-10% of the water needs of humans (Askew, 1996)… Metabolic water is also generated during muscular activity through catabolism of stored glycogen and fat. However, the anaerobic metabolism of glucose to lactate (associated with intense effort) yields only one-third as much water as does complete glucose oxidation, and the metabolic-water contribution from either anaerobic or aerobic effort is still a small proportion of total body water (Askew, 1996).”

Clearly showing that the generated water is likely a net zero, as it equals the amount you lose by evaporation, and what comes from proteins is used to flush out urea. That leaves a deficit equal to the volume of water body needs for anything else, which includes thermoregulation, osmoregulation and regulating the blood volume etc. Also mind you that he is exaggerating and not providing any proper references, in addition to the nonsensical claims about they purity and the toxins etc.

(Bahram Ka) #42

Speaking as as Muslim by birth, some do really adhere, but Muslims are not healthier than anybody else, if anything rich Muslim countries seem to have some of the worst rates of diabetes and hearth disease. Just because something is an old tradition it does not mean it is good.
As Bob and Richard always say, show me the science! :wink:

(Ethan) #43

Of course my statement only applies for those who actually adhere to beliefs and practices (as best possible). If you are fasting all Ramadan and then go out and eat garbage the rest of the year, you won’t be healthier, but you probably would be better of than if you didn’t fast nonetheless.


No water? No thanks.

(Bahram Ka) #45

Again, we are talking about the “advantage” of dry fasting over water fasting. I remain unconvinced, as both scientific or empiric evidence are missing :slight_smile:


To me it is similar to OMAD rather than fasting. Even if Ramadan is in June in Canada (so the shortest night possible, unless you are north of Fairbanks, AK), there are a few hours of night where you could eat nothing but ice cream, pizza and pastries.

(Ethan) #47

In Ramadan, food isn’t the problem when keto; drinking is. You have to dry fast for those hours. Getting enough water intake every day is hard.


Aware, Again depends on the time of the year and the climate. Should not be a problem in Nebraska in December. Saudi Arabia in June another story but the Middle East being closer to the Equater has the benefit of a longer night in Summer. Still from 8PM to 4AM can drink all you want.

I was not talking about people who are keto. I was thinking that since it is not a 24 hour fast dry or not it would have no more benefit than limiting your eating window

(Ethan) #49

I can’t say whether you have done it or not, but I can say that it’s very different once you have done it daily–especially in a “western” country. In the middle east, the world shuts down during that time. You can sleep in the daytime or just leave early. It’s expected that less will get done for many (not all) of the people. But in other countries like the United States, it is a whole different experience. In the winter, its really nothing, but in the summer, its a BEAST! It’s VERY hard to drink enough water between 8:30 pm and 4:00 am–these are the SAME hours you have to get 8 hours of sleep in. But that isn’t even 8 hours. It’s also the same hours you have to eat in. It’s hard to eat anything with a full stomach of water. Then in the other hours, you have all the same responsibilities you normally have, but you cannot drink or eat anything. You have to be outside for child’s soccer practices and games. You have to drive to work in 1.5 hours of traffic each way. You have to conduct all of your business talking with a dry throat and caffeine and salt headache.

It actually gets a LOT easier with keto I think though. You can do OMAD and only eat dinner. Your breakfast can be all liquids, but contain coconut oils and heavy whipping cream that satiate you still. You won’t have the hunger pains. Your food is so much more calorically dense because its fat that you have room for it and water. Nonetheless, there is some struggle to do it EVERY SINGLE DAY for 30 days in a world that does not stop for you or even consider that you are dry fasting.

(TJ Borden) #51

I’ll admit, I’m curious. Especially since when I do extended fasts I generally don’t drink much anyway. I’ve read that durning a dry fast you’re not suppose to even shower. I have a feeling my wife wouldn’t appreciate me going past a couple days. :face_with_hand_over_mouth:

(Chris - Mince meat, not words.) #52

There’s soft dry fasting and hard dry fasting.

Hard dry fasting means you simply can’t touch water. No showers, no washing dishes by hand, no hand washing, etc.

Soft dry fasting allows you to shower and wash your hands and stuff.

It’s really different depending on who you ask, I’ve read (no citations though) that the body allegedly pulls moisture from the surrounding air through the pores.

I have dabbled in 24 hour dry fasts before, and frankly, I never felt dry mouth at all. It was the strangest thing.

(Doug) #53

Very interesting, Razvan. I would never have thought one week was possible, without severe thirst and discomfort. If sweating, then that same day I think I would really need to drink, but have never tried it while fasting.

(So much bacon . . . so little time . . .) #54

Three days is supposed to be about the limit for going without liquid.


Yes, I’ve always been taught 3 days. Interestingly, the guy trying for 5 has never been back to the forum…

(Dan Dan) #56

Dry Fasting has been part of my Regimen and I highly recommend it, just finished a 4 day :smiley:

My monthly routine is OMAD or Every Other Day and just recently added the longer fasts all Dry each ending with a 2 to 3 hour Feast then repeat :heart_eyes::yum::bacon:

Here is a good read :grinning:

(Warning do not read if you are triggered if you have to spend more than ten seconds or are afraid of Sciencey stuff :stuck_out_tongue_winking_eye: In short, Dry fasting allows the body to enter a quicker and deeper State of Rest and Repair in a shorter period of time with greater Results than other methods of Fasting :thinking:)

(Pablo Rodriges) #60

I have done 7 days water fasting, and 3 days dry fasting, the water fast is easy.
The dry fast only side effect for me is dry mouth.

(Doug) #61

Dan, that is quite a presentation. Not sure what all to think, but want to try some of it.

(jketoscribe) #62

I do a dry fast once a year for religious reasons (Yom Kippur). It ends up being 26 - 28 hours or so. It’s not terrible except that no matter what I do (stop caffeine weeks in advance and hydrate really well before the fast) I get a splitting headache in the afternoon–really miserable–almost blinding. It eventually passes. Usually by the time to end the fast I feel pretty good, calm, peaceful, not particularly hungry. Part of that may be the “shiny new soul” feeling that the religious imagery brings.

But it’s still a pretty hard fast to do–takes some working up to, and the all day religious services help because I’m not out in the world where there are things about food EVERYWHERE.

I’ve never noticed the slightest positive impact on my health, weight, etc. --though it’s not negatively affecting me either. So I certainly wouldn’t go out of my way to do it if I didn’t have to for religious reasons.

(Dan Dan) #63

I rarely have a problem with dry mouth but when I do chewing gum solves the problem :smiley:
( Chewing sugarfree gum causes your mouth to increase the production of saliva by 10 times the normal rate.)

(Rob) #64

So it’s not terrible… except when it’s terrible. :grin:

Interesting that this passes before the end… the body and mind is a complicated combo!