Dry Fasting. Is there any science to this?

(A ham loving ham! - VA6KD) #21

There was some research last year I think that worked out what ultimately happens to the molecules in fat when they go through all their various stages of breaking down and eventually leave your body. It was 84% leave as CO2 and 16% H2O… So I guess you’re making water when you’re breaking down fat.

(What The Fast?!) #22

I’m 13 hours into my first dry fast. I skipped my AM workout this morning as I figured that was a bad day without water. It’s supposed to be 70 degrees today and I’m itching to get on my bike…so may have to cut it short. We’ll see what happens!

(Tovan Nhsh) #23

Awesome! Let me know as this is something I’ve been considering as well.

(What The Fast?!) #24

I think coffee may be my downfall. :slight_smile: I should have had a cup and then started the dry fast right after to get to 24 by the next morning at coffee time.

(Tovan Nhsh) #25

Yeah, I was thinking about that as well, caffeine headaches are no joke. Honestly considering laying off the coffee for a few weeks to see how I fell after I “dry out”. But God, I love coffee.

(What The Fast?!) #26

Haha :slight_smile: I did a no coffee fast for a few days and I was fine (no headaches). I’m just a little sleep today.

(Brent) #27

I’m now on 44 hours of my hard dry fast. Honestly it hasn’t been any more difficult for me than a water only fast (at least YET). I do feel slightly more tired but honestly the headaches seem milder than normal. Maybe over-consuming water on your fast can wash out all your electrolytes and cause more/stronger headaches. I don’t know. The only other symptom i’m having is cotton mouth which probably can be expected. I plan to continue on my dry fast for another two days. I might have to downgrade to a soft dry fast because i need to shave but other than that water won’t be touching me. I’ve lost a total of 7 pounds but as we all well know most of that is water weight.

I’m not sure i buy the author of the videos statement that its 3x as good as a water only fast. Where is the proof?

I don’t know if id extend it much beyond 4 days myself (for the dry part at least) because of safety concerns


Hi would proceed with caution, when my father was ill and doctors decided at 94 he wasn’t worth helping recover (he was recovering from pneumonia) they killed him by discontinuing fluids. They said it would take 3-5 days.

(What The Fast?!) #29

I ended my dry fast at 19 hours and started drinking salt water because I wanted to go work out and I knew that dry fasting + cycling is a recipe for disaster. :slight_smile: I did 19 dry and the next 30 regular/wet fasting. Had 2 meals and jumped back into a regular fast again.

I don’t know if dry fasting has its merits or not, but I like working out fasted, so it’s not for me, for now.

(Ivete C) #30

Hi Brent , how did your dry fast end please? Many thanks :blush:

(Todd Aaron) #31

I am 37 hours in to a Dry Fast. Never tried this before but was reading about it after a friend heard about it and did it for 24 hours to get into ketosis faster after a weak day resulted in snacking on crackers and Jif peanut butter and some chocolate… It worked for her and she was back in ketosis in that 24 hour period, so the data about getting there fast appears to be accurate.
I started mine after being in ketosis already.
My weight has dropped 4.5 pounds in the last 24 hours and my waist measurement has gone down 1/4" (I weigh in and measure my waist first thing each morning). I’m assuming the majority of this is water.
I have had a bit of cottonmouth this morning off and on and last night I stayed up way too late and and felt a bit weird at about 3am before getting to bed, but this morning I feel fine.
Considering migrating to a water fast.

I’ve not really found much science on it.

This is one: https://www.karger.com/Article/Abstract/357718

(Doug) #32

Indeed, Keehan - and it’s delightfully pure water, there - I read one advocate of dry fasting and he made it sound like Holy Water, unimaginable in its benefits. :smile:

I routinely have 2 cups of black coffee in the morning, and then perhaps nothing else that day, no food or liquids, when fasting. If I don’t sweat, I don’t get thirsty, at least in the first 24 hours.

If perspiring - and I do fairly heavily when working in heat - then I’d get thirsty very quickly.

I question how significant the benefits of dry fasting over water, etc., fasting are.

I’m still a big guy - over 280 lbs/127 kg, and my internal volume to skin area ratio is a lot higher than that of a thin person. We are always losing water - through exhalation and from the pores in our skin. I would think a pretty skinny person would get thirsty relatively fast, all other things being equal.

(A ham loving ham! - VA6KD) #33

The question is; Is it enough water though? If you’re dry fasting and, say, burning a pound of fat per day (hopeful!), that’s only 75mL of water per day! (Maybe a lot more if you induce a “woosh” however).

(Doug) #34

Good question. Personally, I don’t think one usually really needs any water at all, for a day or two, unless one is really perspiring, or at least feels thirsty. I may be overlooking other causes, but I think it’s the lesser intake of salt, primarily, that results in a lot of water being released through the kidneys as urine, even in the absence of drinking any at all.

(Jeanne Wagner) #35

I hope Brent is OK. He said he was going to do it for 3 days. It’s been 11 days since he said that. Was it Dr. Fung that said that the body can only go 3 days without water?

(Cameron) #36

Well, this thread has gotten me excited about doing another dry fast … have practically forgotten about that while focusing on keeping those carbs under 20g!!! I have done them in the past, longest being 5 days. Felt fantastic throughout (did ‘soft’ dry fasting, so took showers, cleaned my teeth, etc).

Carbs are up a bit today, and I was thinking of water fasting for the next day or so… now rethinking a dry fast instead :+1:

(Candy Lind) #37

Me, too! He hasn’t been on here since the 4th! :scream:

(Jennifer Kleiman) #38

Wildness survival rules say “You can survive for 3 Minutes without air (oxygen) or in icy water. You can survive for 3 Hours without shelter in a harsh environment (unless in icy water). You can survive for 3 Days without water (if sheltered from a harsh environment). You can survive for 3 Weeks without food (if you have water and shelter)”. Obviously there are exceptions (see Wim Hof!) but I don’t think my quest for optimal health is worth risking my life. That said, as a Jew I do a 25-hr dry fast every Yom Kippur without much issue (except sometimes caffeine headache from lack of coffee).

(Ethan) #39

Exactly. People have been doing dry fasting for thousands of years. Jews dry fast a full day at least once a ear, often twice, and up to 25 times a year! Muslims dry fast roughly daylight hours for 30 straight days a year, and may do 6-12 more days a year. This is a long and heathy tradition.


As @Jennifer_Kleiman said I do not see the big deal in 25 hours dry as some of the least healthy elderly Jewish people I know have no problem fasting. However, I am not sure I see a benefit either. Most people gain weight from Yom Kippur because they eat so much at the break fast that they end up having more calories. Still if this can be documented with science I would love to try it. I am very stalled, I have too much excess skin and I still want to get over my IR so if it can help I would love it

@KetoLikeaLady I love your idea of starting the fast after breakfast! The caffeine is a problem for me, this would be a great work around. I always think in terms of a Yom Kippur type fast where you start before breakfast