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Hey All!

Does anyone have any insight / evidence-based advise on what ‘breaks a water fast’ in terms of supplements and vitamins e.g., probiotics, essential amino acids (99% efficiency), Vitamin C, Vitamin D, BCAAs, cod liver oil, black coffee, sea salt, etc.

I appreciate that a water fast means only water (and salt?)! But, if fasting for 5-7 days, it may be wise to supplement to ensure muscle mass isn’t lost, etc.

Any advice greatly appreciated.


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    According to Dr. Satchin Panda consumption of anything other than water, including coffee (no specification of caffeinated or not) will have an impact which you could interpret as breaking a fast. Link and key quote follow.


    “When we drink coffee, is it going to trigger metabolism or certain things in our gut so that the gut will think, "Well, now I have to start working, the rest is over”? And we think that’s where the metabolism or the function of the gut to absorb, or digest this coffee, send that caffeine to liver, and then to brain does kick start right after we drink coffee. Because that’s how we are feeling the effect of coffee in the rest our body, because the stomach started working, it absorbed coffee, it sent it to liver, liver might have metabolized it slightly and started to send it to the rest of the brain and body. And then it gets back to kidney, it gets metabolized and excreted. So then the question is, forget about circadian clock, now if we think about just metabolism and, say, mitochondria function, or even, say, go back to autophagy, and then ask, “Is caffeine breaking the fasting so that it stops autophagy, or it stops something else? Or is there a crosstalk between, say, caffeine receptor and glucagon receptor so that it does?” No, fasting is kind of slightly over. You may not be in 100% fast, but in 40% or 50% fast. So that’s where things become murky, so that’s why we say, “Well, if you can, drink your coffee within this 8-hour, 10-hour, it’s better.” But at the same time we know, going back to the study that we discussed, Ruth Patterson study, they did not consider coffee as food. So when they considered 13 hours overnight fasting, that 13 hours actually included coffee and tea. So in that we know for cancer, reducing breast cancer risk, this 13 hours of fasting can include coffee, black coffee, and tea. So this is where things are really murky. And we tend to error on the safe side, so we tell, well, if you can have that coffee within your eating window, that’s much better. If you can’t, then just have black coffee. At least that will not trigger your insulin response or glucose response. So that’s what we do, we recommend. Rhonda: Just sort of as a side note because you mentioned it, I recently spoke with Dr. Guido Kroemer, who is an expert on autophagy, and he was telling me about a study he had published a few years ago where the specific polyphenols in coffee, decaf or caffeinated… So irrespective of caffeine, it’s just it’s the polyphenols. Satchin: Yeah. Rhonda: They triggered protein de-acidulation, which is one of the triggers for autophagy. So it actually increased autophagy. Satchin: Increased autophagy, yeah. So that’s why we never know, because coffee, or any natural compound, has so many different ingredients that we don’t know the activity."

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      Dr. Patrick mentioned that black coffee will break your fast, but Dr. Fung says no. Typical in the medical field to find two opposing views.

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        A cup of black coffee contains about 1g of carbs - maybe 2g depending on the type/amount of coffee. Even at 3-4 cups per day, you’re talking maybe 5g of carbs and 20 or so calories.

        Does this ‘break’ a fast? Probably depends on how sharply you define a ‘fast’. Are you going to break it, as in totally sandbag all the benefits of it? I doubt it. One of the objectives of fasting is to deplete your glucose so you can run on ketones - 20 or 30 calories is not going to be enough to replenish that (at least, I couldn’t imagine it would be; I’d say it’s a safe assumption unless either of them explicitly refute it

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        I realize this is probably a dumb question, but what about like brushing your teeth? Do you have to actually consume it into the stomach or doing something like drinking water after brushing your teeth affect the fast at all? Getting pretty technical here… just wondering.

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          Hi, in Dr. Patrick’s 2nd interview session with Dr. Satchin Panda (one of her more recent ones) she inquired about a similar thing. She asked about coffee in particular, and I recall him mentioning that protein is something that breaks a fast. It’s not letting me search the transcript or timeline at the moment, but if you search for “black coffee” there should be helpful information there.

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            so, taking Vitamin D while on a fast.. be it a 24hr fast or a 96hr fast, i should wait until my eating time?

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              Hi; I suggest you listen to Dr. Patrick’s interview with Valter Longo on Fasting. It contains a lot of information on how to fast safely. Valter Longo’s book on the Longevity Diet is also very informative regarding fasting.

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                Obviously, anything that contains significant amounts of macronutrients will break a fast. So cod liver oil or protein supplements should be avoided during fasting. Coffe is fine, as long as it doesn’t contain any milk or sugar.

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                  I’d like to know if pure vitamin C breaks a fast. When I take vitamin C it seems to start metabolic processes that were otherwise blocked.

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                    Carbs and BCAAs activate insulin and will stop autophagy