Absolutely unexpected. A clarification though, which maybe you were aware of: the fasting period studied is no eating for 10 days straight, not intermittent fasting Ramadan-style. Given how counterintuitive this result is, I'm not sure I'd jump to the conclusion that intermittent fasting has the same effect.
Muslims that I know tend to gorge themselves every night for iftar. I would expect the body's reaction to be completely different than the 10 day fast studied here.
Unfortunately this is very true. The intention I feel is to rest the body during Ramadan, eat only what you need, maybe a bit less to actually feel hunger, become more spiritual, etc. But where I am, it is literally the opposite; people make huge feasts, with round two being sweets and dessert. EVERY SINGLE DAY. Add to that the lack of motion and activity and at 30 days we’ve put on 10 kg. Sorry to put this under your comment xD
Its not really unexpected. One could also think that building muscles during high caloric restriction diet/pure fasting is impossible but growth hormone works wonders for that.
Everyone's body is different, but you would need to be underweight or be severely malnourished to suffer from clinically defined refeeding syndrome after a three day fast. If you are normal to overweight and consuming electrolytes during the fast you are probably going to be fine.
I had a significant diabetic-like response from refeeding after only 3 days of fairly extreme fasted exercise. A week later my cholesterol rose above 400 and I was producing about 1 gallon of urine per hour. My PCP freaked out over my blood work and called me on a Sunday. I was already quite lean from the start, and planned to go longer, but I was having trouble standing, so I broke the fast, and quickly lost control of my eating. Woke up with swollen purple eyes, pain everywhere.
That was many years ago. I’d like to try again with the right mineral support and lower intensity now that I actually have some fat to burn, but I don’t think I have the mental strength or focus for it.
Is the parent getting enough magnesium? Also avoid foods with phytic acid when taking magnesium, since phytic acid may reduce the amount of magnesium and other minerals absorbed by the body.
A review published in The Journal of the American Osteopathic Association found Vitamin D can't be metabolized without sufficient magnesium levels, meaning Vitamin D remains stored and inactive for as many as 50 percent of Americans.
"People are taking Vitamin D supplements but don't realize how it gets metabolized. Without magnesium, Vitamin D is not really useful or safe," says study co-author Mohammed S. Razzaque, MBBS, PhD, a professor of pathology at Lake Erie College of Osteopathic Medicine.
...
Patients with optimum magnesium levels require less Vitamin D supplementation to achieve sufficient Vitamin D levels.
Perhaps I am a bit naive, but what is the potential harm in fasting for such a timespan? The point of fat tissue is to maintain the body when calories are not available. Unless starting from a position of anorexia, most people have ample reserves to supply them for such a duration. With medical supervision, one man went over a year without eating[0].
Also not a doctor, but from what I've read for some people it could lead to starvation and death. Basically when you are fasting, your body starts to eat your fat instead, so if you have some underlying disease, or if you are extremely lean, or e.g. a high-maintenance sports person, you are probably at very serious risk.
That said, 10 days seems a bit short for death, but yeah if you are in one of those 3 groups (high sports, extreme low fat, or with some disease) I would not take fasting lightly.
> It's not a surprise that his lifespan was shorter than average.
Given all of the purported health benefits of fasting I see touted on HN, and given how long he fasted, if anything I'd expect him to have lived to 100.
Allegedly health problems from obesity and stomach bleeding killed him. Questionably related to the fast,probably related to the health problems that got him to do the fast in the forst place.
That was 25 years after his fast, but there have been other cases with complications
E.g. one lady (1st case in the lnk below) who fasted for 4 months ended up in the hospital for 3 weeks with cardiac arrhythmias and they also found her heart tissue muscles were scared and filled with holes (I believe thats what vacuolated means)
Without any cause listed dying at 50-51 is not rare at all and should not be assumed to be related to a particular cause. In fact, life expectancy of those born on 1940 was 60.8 years, making it within 10 year of the average, something totally normal IMHO (it's like today, with a 78-year life expectancy, someone dying at 68 years old, totally not surprising).
Life expectancy is a tricky stat. One of those cases where mean vs median vs mode is really important. Especially when talking about a period anchored in a global conflict with vast civilian casualties.
I just ended a 16 day fast today. Any caloric intake was limited to miso soup broth (< 35 cals) and a pickle every few days. Lots of coffee, black tea, some diet sports drinks and water (with electrolytes added). Was surprisingly easy, physically, but I also have a relatively high BMI. I ended because 1) it gets very boring, 2) I was constantly consumed with the idea that I was in a fast -- it could basically crowd out any other thoughts and my work suffered a bit.
I would categorize the mental focus struggle into two parts, the first being the first four days of the fast, where I was in an almost anxious, reflexive state of wanting to end the fast. After the fourth day this quickly gave way to a low level hum of fasting related thoughts. Kind of like the difference between acute, sharp pain and a dull aching pain.
I'm curious to know how your experience ending it today is like compared to before you started it. Do you feel like it's easier or harder to eat less compared to before your fast?
Easier to eat less by nature since my stomach is smaller, but overall I would say there is no expectation that the fast would magically regulate my an unhealthy relationship with food/consumption. My poor habits have to be addressed separately (particularly my beer consumption rose quite a bit in the last few years).
The fast served as a kickstart toward weight loss and in a way a test of my resolve.
I'm continuing to fast fwiw, doing what is known as "rolling 48s" which is just a large meal every other day. I went for a couple mile jog last night after starting to eat again and felt pretty good so I'm going to keep doing that while fasting for short periods and see where this takes me.
> The purpose of our study was to evaluate the impact of short-term high-caloric feeding and fasting on bone microarchitecture. We hypothesized that both high-caloric feeding and fasting would have negative effects on microarchitecture.
I know it shouldn't have a huge impact on my assessment of a study, but when I see that they were looking for not-x and found x, it makes me feel substantially more confident in the result. It only guarantees that they were not p-hacking, and doesn't have any bearing on other aspects that would affect the validity of the results.
I came to the comments first assuming there'd be p-hacking (a broad amount of parameters would be tested trying to find some that have "statistical significance", which is bogus and commonly referred as p-hacking). I am a bit tired of seeing very promising articles, becoming hopeful then just to read HN comments on why it's ridiculously flawed (I do get HN tends to be negative, but in scientific articles in a good way, I prefer no-results that fake positive hopes).
Very happy to see your comment and I def agree, if looking for specifically not-x and found x it also increases my trust in an article A LOT.
I’m willing to burn my karma on this to push back on some misinformation. Fasting for 10 days is safe. You won’t get refeeding syndrome. Pretty much any person can do it barring obvious exceptions. I’ve done it a bunch of times and I’ve read all the papers. If you think I’m in error please correct me with a citation and I’ll read it.
> The underlying causative factor of refeeding syndrome is the metabolic and hormonal changes caused by rapid refeeding
> The clinical features of the refeeding syndrome occur as a result of the functional deficits of these electrolytes and the rapid change in basal metabolic rate.
> Any patient with negligible food intake for more than five days is at risk of developing refeeding problems
I've done few fasts as well, 10 days IMHO is in the limit and you can definitely get refeeding syndrome, but probably just light one. Of the few times I did 7+ days fasts, I only got it once, and that was when I ate a lot for breaking the fast. Which obviously I shouldn't have done in retrospective, and the only symptoms was moderate stomach pain for few hours IIRC.
I do agree that at 10 days (YMMV!) you probably don't need those crazy refeeding ramp-ups of broth and soups for 1-2 days then soft foods for another few days, etc, but also don't just stuff yourself until you cannot move! Since you can chose, take a couple of light/easy to digest meals before going back to normal.
This document from some Canadian health agency on how to handle patients participating in hunger strikes provides a good overview of the various conditions and risk factors for refeeding syndrome and much more. If you are into fasting it's an interesting, if poorly organized, document:
I fast regularly. It is pretty well known that our bodies are extremely good at preserving itself during fasting. I would even risk saying that our bodies don't work optimally until we are 2-3 days into a water fast. I feel better and lighter when I am fasting. Having to eat after a week of fasting almost feels like nuisance. Don't get me wrong, it still tastes incredible, but you know that this feeling of lightness is going to be lost with it.
One thing bodies are very good at is preserving stuff when there is little of it, while fasting. Did you know you will be wasting much less muscle if you go on a complete fast than if you do calorie restricted diet? (please don't do calorie restriction)
So this result is interesting but not really surprising to me. I would assume that if our bodies work overtime preserving stuff there is a possibility they will do the same to calcium. After all we are already built to send excess calcium into our bones.
> Don't get me wrong, it still tastes incredible...
I must be doing something wrong. Every time I've tried fasting for more than a day, breaking the fast was painful. My throat always hurt too much to enjoy the meal.
I keep hearing stories like this so I'm sure it's a common experience. But the one time I fasted for a week, the last 36 hours were a torture of continuous hunger, and my body has been highly resistant to more fasting since. I used to do regular multiday fasts but haven't done any since.
If you try it, it's probably best to follow the advice to stop when it gets bad and don't tough it out.
the longest that I fasted was about 3 months and the biggest challenge that I faced was that if you omit protein from fasting then you have this weak/tiredness feeling throughout the time that you're fasting. what I found is that if you drink One of those 30g protein shakes everyday and a vitamin B complex vitamin (which supposedly breaks down lipids/fats) during the fasting, those feelings went away. on average I lost about 1 lb per day of body weight by doing such a fasting,.. and then after about 2 weeks of fasting it appears that your stomach gets smaller, and you become less hungry as a result, and the desire for food itself decreases.... during that 3 months I lost about 50 lb, and I think only because I would cheat once per week on Sunday.
Back in the 90's I lost 120 pounds on a multi-month protein shake "fast" ... and then gained it all back plus more. In total, despite the wonderful if brief relief from morbid obesity, it was a highly negative experience that I don't recommend, at least for weight control.
"protein shake fast" is not a fast. It is a calorie restriction diet. Probably the worst kind you can imagine.
I lost 60 pounds once, then regained it back and then some. I lost it again but the second time I made it my mission to understand what I do and make it stick. It seems to be working.
It is better to get healthy to loose weight that loose weight to get healthy. With healthy habits and healthy food your body will naturally shed unnecessary weight over time.
The second time I lost weight, for good, I focused on building good eating habits. Learning new healthier recipes (to displace unhealthy food). Running every day. Intermittent fasting rather than restricting calories. Building metabolic flexibility so my body is good at living off of its fat stores.
I was loosing up to 15 pounds a month for three months straight while not feeling hungry.
This is probably because your body has atrophied fat burning metabolic pathways.
I would suggest to start with regular daily fasting. This means you eat within short window of time every day (max 4-6h) and the rest you get by with no calories. It takes about 2 weeks to a month for a person to adjust depending on your overall health, age and whether you are insulin resistant.
Once you get adjusted, you can try to restrict carbs a bit. Carbs are responsible for most of the hunger feeling. When I cut carbs my hunger ended completely. Cutting carbs (with restricted eating window) will force your body to adjust to functioning on your fat stores alone.
Please, be mindful none of this requires cutting calories. You can eat as much as you want, just keep your feeding to a short window every day and try restricting carbs and replace them mostly with fats. Ideally you would also want to pay attention to what kind of fats -- refined ones are usually the worst.
Hunger is your body signalling inability to get fuel for its critical processes. Given that most of us have hundreds of thousands of calories of fat (even if you look relatively lean), it is a bit preposterous idea that should be understood by your body having large stores of fuel but being unable to access them when it needs.
This might be because there is insulin present (any levels of insulin basically block your fat metabolism). Or it might be because you have never exercised your fat metabolism and now suddenly you require it to provide a lot of energy which it is not equipped to do.
This is solved by simply exercising it which means allowing your body to metabolise your stomach content and then waiting some more so that it has to reverse its processes to start metabolising fats. 16-18 hours is what is necessary to get there and that's why 4-6 hour eating window comes from -- so that you can train your fat metabolism a bit, every day.
With healthy fat metabolism you should be able to go on a prolonged fast and it should be enjoyable.
ideally one shouldn't even need to fast, unless we have to spend several months with less food in the cold, semi-hibernating like some of our ancestors. I know in our modern society, more than half people are now overweight, but ideally we should reach our ideal weight, and have few meals per day with vegetable rich diet
I'm at 60kg I think, for 1.83m, it's not underweight for my body shape - long legs, thin hip, arms & wrists, I often have huge meals, that way I can spend at least 20h without eating, but doing multiple-days fasting would be difficult unless I stay in bed
People think I'm skinny and I'm 1.82m, fairly narrow build, and usually 78kg-82kg.
I've never worried about what I eat. My weight has been more or less constant. I know other people have to be very careful or they easily put on more weight. There is very little fat on me (maybe I could go a little bit leaner but I mostly don't worry about it).
That said, I think extended fasts are not about managing your weight, they're intended to force your body into a different mode. I'm pretty sure they're not an efficient way to reduce your weight (more activity + a bit more control over what you eat would be better). If you want to increase your weight without being fat then resistance training + eating more.
exactly, usually every week, I've a few days with high fruit, depending on the season. The rest of week if more standard (rice, onions, garlic is my simple go-to) and with that one I don't need more than 1 large meal a day
Long fasting is something trendy, but I don't believe in its long term benefits, because the goal is to lose weight and reach our own ideal weight (usually between 18 and 24 BMI depending on your body shape). Many ways to achieve this: vegetable super rich diet, eat less often, bike for commuting or for everything, minimalism (depend less on things & services)
66 comments
[ 493 ms ] story [ 2539 ms ] threadProlonged fasting is known to increase growth hormone production
Growth hormone promotes growth of bones and cartilage
They were also taking a small amount of vitamin D. Not sure how much that matters, but it's worth mentioning.
Also, certain conditions (including but not limited to T2 diabetes) can make fasting like this dangerous. I believe kidney problems are another one
That was many years ago. I’d like to try again with the right mineral support and lower intensity now that I actually have some fat to burn, but I don’t think I have the mental strength or focus for it.
from https://www.eurekalert.org/news-releases/891683:
A review published in The Journal of the American Osteopathic Association found Vitamin D can't be metabolized without sufficient magnesium levels, meaning Vitamin D remains stored and inactive for as many as 50 percent of Americans.
"People are taking Vitamin D supplements but don't realize how it gets metabolized. Without magnesium, Vitamin D is not really useful or safe," says study co-author Mohammed S. Razzaque, MBBS, PhD, a professor of pathology at Lake Erie College of Osteopathic Medicine.
...
Patients with optimum magnesium levels require less Vitamin D supplementation to achieve sufficient Vitamin D levels.
phytic acid: https://www.webmd.com/diet/foods-high-in-phytic-acid
When you eat foods high in phytic acid, the molecules bind with certain minerals in your digestive tract, including:
Calcium Magnesium Iron Zinc Chromium Manganese
Once this occurs, your body no longer has access to these nutrients.
In higher doses, it's a first-line laxative administered prior to routine surgery.
Blood tests confirm my levels are right on the money.
Not a doctor, not medical advice.
[0] https://en.m.wikipedia.org/wiki/Angus_Barbieri%27s_fast
That said, 10 days seems a bit short for death, but yeah if you are in one of those 3 groups (high sports, extreme low fat, or with some disease) I would not take fasting lightly.
Odd how this part often gets ignored when his example is cited.
It's not a surprise that his lifespan was shorter than average.
Given his death was a quarter of a century after he finished his fast, I'm not sure it makes the causal implication you are suggesting.
Given all of the purported health benefits of fasting I see touted on HN, and given how long he fasted, if anything I'd expect him to have lived to 100.
Allegedly health problems from obesity and stomach bleeding killed him. Questionably related to the fast,probably related to the health problems that got him to do the fast in the forst place.
E.g. one lady (1st case in the lnk below) who fasted for 4 months ended up in the hospital for 3 weeks with cardiac arrhythmias and they also found her heart tissue muscles were scared and filled with holes (I believe thats what vacuolated means)
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1238550/pdf/wes...
I'm a fan of a 7 day prolonged fast, but not for anything longer
"Remember, to be healthy you need to have 5 small meals during the day. Don't let yourself get hungry," cry the Western dieticians.
The fast served as a kickstart toward weight loss and in a way a test of my resolve.
I'm continuing to fast fwiw, doing what is known as "rolling 48s" which is just a large meal every other day. I went for a couple mile jog last night after starting to eat again and felt pretty good so I'm going to keep doing that while fasting for short periods and see where this takes me.
I know it shouldn't have a huge impact on my assessment of a study, but when I see that they were looking for not-x and found x, it makes me feel substantially more confident in the result. It only guarantees that they were not p-hacking, and doesn't have any bearing on other aspects that would affect the validity of the results.
Very happy to see your comment and I def agree, if looking for specifically not-x and found x it also increases my trust in an article A LOT.
Keep your phosphates ( and other electrolytes) normal and don't break the fast with lots of carbs
> The clinical features of the refeeding syndrome occur as a result of the functional deficits of these electrolytes and the rapid change in basal metabolic rate.
> Any patient with negligible food intake for more than five days is at risk of developing refeeding problems
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2440847/
This is something that applies to holocaust survivors and hunger strikers.
I do agree that at 10 days (YMMV!) you probably don't need those crazy refeeding ramp-ups of broth and soups for 1-2 days then soft foods for another few days, etc, but also don't just stuff yourself until you cannot move! Since you can chose, take a couple of light/easy to digest meals before going back to normal.
https://cchcs.ca.gov/wp-content/uploads/sites/60/CG/HSFR-Car...
One thing bodies are very good at is preserving stuff when there is little of it, while fasting. Did you know you will be wasting much less muscle if you go on a complete fast than if you do calorie restricted diet? (please don't do calorie restriction)
So this result is interesting but not really surprising to me. I would assume that if our bodies work overtime preserving stuff there is a possibility they will do the same to calcium. After all we are already built to send excess calcium into our bones.
I must be doing something wrong. Every time I've tried fasting for more than a day, breaking the fast was painful. My throat always hurt too much to enjoy the meal.
If you try it, it's probably best to follow the advice to stop when it gets bad and don't tough it out.
I lost 60 pounds once, then regained it back and then some. I lost it again but the second time I made it my mission to understand what I do and make it stick. It seems to be working.
It is better to get healthy to loose weight that loose weight to get healthy. With healthy habits and healthy food your body will naturally shed unnecessary weight over time.
The second time I lost weight, for good, I focused on building good eating habits. Learning new healthier recipes (to displace unhealthy food). Running every day. Intermittent fasting rather than restricting calories. Building metabolic flexibility so my body is good at living off of its fat stores.
I was loosing up to 15 pounds a month for three months straight while not feeling hungry.
I would suggest to start with regular daily fasting. This means you eat within short window of time every day (max 4-6h) and the rest you get by with no calories. It takes about 2 weeks to a month for a person to adjust depending on your overall health, age and whether you are insulin resistant.
Once you get adjusted, you can try to restrict carbs a bit. Carbs are responsible for most of the hunger feeling. When I cut carbs my hunger ended completely. Cutting carbs (with restricted eating window) will force your body to adjust to functioning on your fat stores alone.
Please, be mindful none of this requires cutting calories. You can eat as much as you want, just keep your feeding to a short window every day and try restricting carbs and replace them mostly with fats. Ideally you would also want to pay attention to what kind of fats -- refined ones are usually the worst.
Hunger is your body signalling inability to get fuel for its critical processes. Given that most of us have hundreds of thousands of calories of fat (even if you look relatively lean), it is a bit preposterous idea that should be understood by your body having large stores of fuel but being unable to access them when it needs.
This might be because there is insulin present (any levels of insulin basically block your fat metabolism). Or it might be because you have never exercised your fat metabolism and now suddenly you require it to provide a lot of energy which it is not equipped to do.
This is solved by simply exercising it which means allowing your body to metabolise your stomach content and then waiting some more so that it has to reverse its processes to start metabolising fats. 16-18 hours is what is necessary to get there and that's why 4-6 hour eating window comes from -- so that you can train your fat metabolism a bit, every day.
With healthy fat metabolism you should be able to go on a prolonged fast and it should be enjoyable.
I'm at 60kg I think, for 1.83m, it's not underweight for my body shape - long legs, thin hip, arms & wrists, I often have huge meals, that way I can spend at least 20h without eating, but doing multiple-days fasting would be difficult unless I stay in bed
I've never worried about what I eat. My weight has been more or less constant. I know other people have to be very careful or they easily put on more weight. There is very little fat on me (maybe I could go a little bit leaner but I mostly don't worry about it).
That said, I think extended fasts are not about managing your weight, they're intended to force your body into a different mode. I'm pretty sure they're not an efficient way to reduce your weight (more activity + a bit more control over what you eat would be better). If you want to increase your weight without being fat then resistance training + eating more.
exactly, usually every week, I've a few days with high fruit, depending on the season. The rest of week if more standard (rice, onions, garlic is my simple go-to) and with that one I don't need more than 1 large meal a day