So I’m going to be hitting day 14 of my fast on Monday. Honestly, I feel fine, aside from being a little tired, and not hungry at all. I was thinking about just continuing it.
Is there anything I should be seriously concerned about? I don’t have any existing health issues aside from being overweight. Anyone else have experience with a 14+ day fast? When trying to do research online I just come across random websites that just seem to want to sell me something, so I can’t seem to find any reliable facts or personal feedback.
Be careful about how you start eating again when you decide to do so. I don’t know the degree of risk you face, but there is such a thing as “refeeding syndrome,” and it has been known to be fatal in quite a few cases. You can avoid such problems by learning how to properly resume eating.
Yeah, I’ve read that you have to ease into it. Broth/bone broth/stock. Some people have rules of thumb, like for every so many hours fasting, you have to ease into it for X hours. I always broke those though. (I’d fast 4.5 days and – at best – have a small meal an hour or so before eating a larger meal; I usually just jumped to the larger meal.)
Never fasted longer than 4 days so can’t help. Just be careful refeeding like everyone has said. You need to “wake up” your digestive system gradually.
@jimmyv Congrats on your 14 day fast.
Recently I’ve done a 14 day fast myself, I would say if you have no hunger and no cravings there is not really a reason to stop your fast. Although in my opinion the longer you go the more careful you have to be whit re feeding. After fasting for 14 it took me ~4 days until my guts started to work properly. Many people fast longer than that but the longer you go the more care you will have to take how do you approach refeeding.
Everyone touched on how to refeed, but my biggest concern with longer fasts is loss of lean body mass (especially muscle).
I know that Jason Fung, and others make claims fasting is muscle sparing, but I have yet to see scientific evidence that backs that up. Superficial levels of growth hormone is not anabolic, and I don’t think anyone can provide the studies that support that the small rise from fasting would be either.
Both fasting and calorie deficits are catabolic, so I pair my fasts with resistance training that focuses on heavy compound lifts (low bar squats, dead lifts, standing shoulder press, bench press, etc).
I think extended fasting is great, but I think the preservation of lean body mass is paramount. Muscle mass and bone density is huge driver of health, and also metabolic rate.
Dr. Stephen Phinney agrees with you, and it’s his major publicly-expressed concern with extended fasts. I have the impression that his private view is less opposed to longer fasts, but that he doesn’t feel he can do the nuances justice and is just trying to keep people safe.
Having done both many longer term fasts (up to 5.5 days) and many, many shorter fasts, and having DEXA scans, I was able to increase my fat-free mass and lose fat mass over the course of a year. Whether that’s typical or not, I don’t know, as it was after shoulder surgery for me.
And, I was a pseudo-bodybuilder when I was younger, so it’s probably easier to regain the mass I lost than to build it new.
After looking back at my data, though, the lowest fasting insulin I got was during periods with a lot of fasting. I also lost the most “weight” (always hard to tell - without a DEXA scan - what makes up that “weight”) during those periods. So, I’m going to try to get at least one 36 hour fast per week again. Not sure about fasting longer than that during a pandemic, as longer fasts supposedly affect the immune system. I did only one 4.5 day fast all of last year, and that was before the pandemic.
There is a certain amount of unavoidable protein loss each day. The study that was used to determine the dietary recommendation of 0.8 g protein/kg lean body mass showed a scatter plot that was all over the place. While the mean average was 0.6 (0.8 was set as the recommendation in order to give a cushion), some people had a much higher and others a much lower nitrogen loss. (The nitrogen loss was converted into an estimate of the equivalent amount of protein.)
What this means is that there is no way to avoid losing some lean tissue from fasting. Since you are not eating, your source of energy is fatty acids, and there is no way to turn a fat into an amino acid because fats and glucose are composed of carbon, hydrogen, and oxygen. We get nitrogen only from eating protein; can’t get it from atmospheric nitrogen, which is inert.
Don’t you have to quantify this in terms of length of time? For instance, I assume I lose very little to no lean tissue for my normal fast of 15-16 hours daily of fasting (2 meals a day).
At some point, you’ll lose some “mass”, but it’s tricky as to what that is. Perhaps if you’re fasting 4.5 days (my favorite long term fast, as you quit eating Sunday evening, then eat sometime Friday), the small amount of mass you lose is the kind you want to lose anyway?
And even if it is muscle mass, who knows how quickly that comes back?
Even Phinney seemed to think that some fasting was good, but at a certain length, he got concerned about losing mass (what some might call “autophagy”, as he jokingly referred to it). But there’s no way to tell what is being lost (even a DEXA scan would have a hard time with that), and whether that was “useful”.
Let’s not confuse intermittent fasting (i.e., the nightly fast) with extended fasting. As long as there is protein coming in every day, the labile pool of amino acids can hold enough to make up for the loss of amino acids to deamination. (The nitrogen from this deamination process is used to generate NO for regulating blood pressure; the excess gets converted into uric acid and excreted.)
The labile pool can contain only so much, however, so it’s when we fast for longer than a day or two that the need for nitrogen starts causing the body to scavange it from lean tissue. When there are suitable candidate proteins for autophagy, this is a good thing, no? There is always some autophagy going on, because proteins have their lifespans (apparently the range is from second to years, depending on the protein in question), but one of the benefits of fasting is supposed to be an increase in the rate of autophagy. Generally the amino acids liberated by autophagy return to the labile pool, but there is always that ongoing and unavoidable loss to deamination.
I really wonder, Paul. Some of the stuff he has said makes it sound like he denies autophagy and the drastic decrease in net protein consumption by the 3rd or 4th day of fasting that was well documented by George Cahill and others prior to Phinney’s work. There’s “erring on the side of safety” and there’s just plain being wrong.
It’s come up before - you’re right, longer fasting really just isn’t his thing and at this point he’s not in the mood to worry too much about it, I think. It does seem like perhaps some of the things that get attributed to him - things that have appeared on the Virta Health website - were likely not written by him or actually said by him; my opinion.
Doug, it is really a shame that there’s so little good, rigorous research on fasting humans. I agree that muscle mass and bone density are a concern. Fung’s point is that it would be pretty stupid, evolutionarily, to use up muscle while starving, since the need to get out there and hunt and gather will be pressing.
That makes sense to me, but it only goes so far - if zero protein is taken in, then there definitely will be net loss, since some is lost. The rate of loss does fall off quick when fasting, though - down to 15 or 20 grams per day in just a few days of fasting. If it was only muscle that was being used, then that would be one pound of muscle every 4 or 5 days. In practice, it looks to me like it’s usually far less than that, due to skin (1/6 of our weight), etc., being used.
Some people actually report gaining lean mass while fasting. To me, this would be impossible, and most likely an artifact of DEXA scans or similar picking up in creased hydration in certain tissues. However, many people are fasting for comparatively long periods these days, 30, 40 days, and reports of muscle loss are few if any. During the refeeding period some dramatic things happen as far as rebuilding - perhaps this offsets part of any muscle consumption? There are also rare cases of extremely long fasts, 100 days, 200, up to the famous 382 day one - and people usually end up quite normal, i.e. in no way do they lose a harmful amount of muscle.
The increase in growth hormone is more than superficial. The one case I’ve seen was a guy doing a 40 day fast, and the highest growth hormone level was on Day 26, an increase of 1251% over normal, which is profound (9.86 ng/ml versus 0.73 measured before the fast began).
(Page 385.)
In general, the amount of fat a person has to burn does seem to make a difference, i.e. leaner people use more nonfat mass while fasting, and have a markedly harder time fasting for multiple days. In the end, perhaps there is more individual variation than we know about…?
My only advise isn’t positive, I’ve never done that long myself but I used to do 7/8 days once a month for a while and completely trashed my metabolism. I’m now on almost year 2 of fixing it so don’t push it too far. I’d also say unlike most fasts when you start hitting lengths like this break it easy, you may go into a binge once you eat so be ready to fight that. I’d always break mine (the right way) then about 1hr later I’d kill whoever stood in between me and the fridge.
This is true, for me. When I was much heavier, a 4.5-5.5 day fast was nothing…and I’d exercise several times while doing that.
Now, that I’m leaner and have more muscle mass, the fasts are harder. I don’t even attempt to exercise while fasting a long time.
I’ve been in conversations with very lean, muscular people who can’t fast 24 hours. Ted Naiman is anti-fasting, but he’s also very lean and many people who follow him are lean or muscular or attempting to get there.
I fasted a ton for a year and gained lean mass and lost fat mass, verified by DEXA scans.
Dude, I’ve been doing this for 7+ years and fasting (many, many, many, many 3.5-5.5 day fasts and 36 hour fasts and 22 hour fasts) for 5.5 years of that. I don’t confuse short term and long term fasting.
But I think between Fung and Phinney, my money is on Fung. He and his staff have helped THOUSANDS of patients through fasting. What has Phinney done, save look at data?
It’s like all the people who poo-pooed Atkins because he had no RCT data. He was correct; they were not.
A note about Atkins, too. Adele Hite remarked on the people who started with Atkins don’t do things like worry about macros. I’m an Atkins guy, having started many times before January, 2014, but thinking I “had” to have carbs to exercise. Even though I felt great every time I did Atkins, I thought I need carbs to ride my bike the 90+ miles per week I was riding it.
It wasn’t until January, 2014, that I started Atkins for good. (Though I never did the increase in carbs he recommended.) That’s why some of us don’t really “do” “macros” (and still find no use for them).
How much weight have you lost? I think it’s awfully interesting! Wow!
How overweight are you?
So you’re not hungry at all? Do you get hungry ever?
I’d love to do a detox. They say we should only eat when we’re hungry?
I eat once a day 5-6 pm with a snack around 9pm. Don’t do a feed again except coffee till the next day around 5-6 pm.
I’m famished around 6.
I am not a physician, or my warning would have been more precisely phrased. I do know, however, that refeeding syndrome got its name during World War II, as prisoners of war and liberated concentration camp survivors, who were given food after a long period of starvation, would sicken and die.
The mechanism and how a physician should deal with it is detailed in one of Dr. Phinney’s lectures to a Low Carb Down Under conference, available on YouTube. The problem has to do with what happens to potassium levels when the person starts to eat freely again, and I’m sorry, but I don’t remember all the details or I’d provide them. This risk is one of the reasons that Dr. Phinney is opposed to long-term fasting, and why even Dr. Fung advises not to fast for more than about three days, except under medical supervision.
(I barely have time for my admin duties on this site, much less trying to maintain a site of my own, lol!)
Same here - long time Atkins fan and never increased my carbs either. And when I switched to keto I never tracked or worried about macros - just increased the fat which helped reduce my hunger and kept me from getting so bored with the food.
