
Is fasting safe? A review of adverse events during water-only fasting (2018) - rfreytag
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5819235/
======
lqet
I am confused by some of the comments in here who seem to see no food intake
for more than 36 hours as dangerous or even pathological or assume that you
need to somehow "prepare" for that or take certain precautions. Is this a
cultural thing?

When I was I student, I ate one meal a day, maybe some snacks in between. Very
often, I went without food for a day, simply because I was too lazy / too
emerged in some project to leave the house to buy food. Eating the last meal
on Sunday evening, not eating on Monday, eating again on Tuesday evening - 48
hours without food. I did this many, many times, and still (in my early 30ies)
do it occasionally, again just because I am too lazy to buy food sometimes. It
never occurred to me that this could be considered "fasting", because neither
did I feel any different after going 48 hours without food, nor did I lose any
measurable amount of weight from it.

Days, weeks or even months without food was pretty much the norm until ~150
years ago. If a day, or even a week without eating would be seriously
dangerous to your body, mankind would've become extinct a long, long time ago.

~~~
nabla9
You would be surprised how many people have gone trough their life without
experiencing real hunger.

I was doing short weekend hike with a friend and the shop we intended to visit
was closed. We had to walk six hours without eating. My fried started to panic
and would have called emergency services because he was feeling so weak that
his hands started shaking. I had to explain it to him several times that if
you sit down for a 15-20 minutes the shaking goes away as the body converts
fat to glucose. He was convinced that he would die from walking hungry. Yes,
physical exercise while hungry sucks, but you don't die in several days.

~~~
lqet
> He was convinced that he would die from walking hungry.

Do you think that this is a cultural phenomenon? I cannot imagine a person
having constant access to food, everywhere, so that he never walked a few
hours without eating. You would have to carry a backpack full a snacks
everywhere, or you would somehow make sure that a store or some food place is
near you, which seems pretty inconvenient.

~~~
nabla9
> I cannot imagine a person having constant access to food, everywhere

I think it's very common in urban environment with middle class people. You
may feel little hungry but you eat within hour or so, never hunger pangs or
real weakness. When you do hard exercise, you carry sport drinks and snacks.
It's not that hard.

It can be different for poor people in the same culture. Maybe the lack of
shared experience contributes to the lack of empathy. When people see poor
person walking on the street with hunger pain expression in their face, how do
people interpret it? If they don't have a shared experience, hungry person may
look just angry.

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geowwy
Conclusion:

>> To our knowledge, this is the most comprehensive analysis of adverse events
experienced during medically supervised, water-only fasting conducted to date.
Overall, our data indicate that the majority of adverse events experienced
were mild to moderate and known reactions to fasting. This suggests that the
protocol used in this study can be safely implemented in a medical setting
with minimal risk of a serious adverse event.

~~~
leereeves
But is it safe to fast on our own in a non-medical setting?

If only "the majority" of adverse events were mild to moderate known
reactions, how many were severe? How many were unusual? And what does the
medical setting provide (clearance, planning, monitoring, intervention) that
people fasting on their own might lack?

~~~
baldfat
It's safe because humans had to fast. Think about it, humans didn't have a
fridge and fast food. Humans had to go through fasting and in now way except
the elite have 21 meals a week.

When you read books in history winter sucked because the lack of food. They
would normally ration and it would literally be feast or famine. Just the way
we evolved was to be able to do this.

~~~
kasperni
While I believe fasting is safe your logic is flawed. If I following your
logic, what would the answer be to "Is it safe to not brush your teeth or
visit the dentist"

It's safe because humans had no access to dental hygiene. Think about it,
humans had neither toothbrush or toothpaste. And there where no dentist.
Humans had to go through life without proper dental hygiene.

Obviously, not taking good care of your teeth is not a good idea. Even though
our ancestors didn't.

~~~
lawlessone
>Obviously, not taking good care of your teeth is not a good idea. Even though
our ancestors didn't.

TBF our ancestors weren't eating much

~~~
baldfat
Didn't say it was a benefit (I think there is a benefit though personally). My
logic was that it was a common occurrence that humans evolved with the ability
to go through long periods of fasting. You can go 40+ days without eating and
live and that seems pretty amazing how the human body has adapted.

Also looks like cleaning our teeth goes much further back then tooth paste
(19th Century Invention) [https://recipes.howstuffworks.com/ancestors-eat-to-
clean-tee...](https://recipes.howstuffworks.com/ancestors-eat-to-clean-
teeth.htm)

------
mirceal
For people that come into this and think: “wtf is wrong with someone that they
want to starve themselves” there is more to this than meets the eye.

There is more than one type of fasting (more than one protocol - thowing this
here: IF with 16:8/18:6/omad, ADF, 5/2, Extended) and there is some science
backing this up. some of the benefits of fasting are mind blowing but it’s
hard to “swim upstream” when some of our beliefs are so entrenched (examples:
not eating is going to slow your metabolism down, not eating is going to make
you lose muscle mass, it’s a sing of mental health issues, it’s a eating
disorder, breakfast is the most important meal of the day, you need to eat X
time per day to keep your metabolism working)

go to reddit and read the side bar for r/fasting and r/intermittentfasting and
do a little bit of research/keep an open mind.

~~~
draxofavalon
Agree, keep an open mind and don't be affraid to try. I don't know how to
categorize my IF, I've been doing it for 4 years. Tuesday and Thursday a snack
at 14 and dinner around 21. Friday night, saturday and sunday I eat whatever I
want. All other days just tea or cofee.

I'm 42 and I feel better than ever.

~~~
iambateman
Just to make sure I understand...

Sunday: coffee Monday: coffee Tuesday: snack and dinner Wednesday: coffee
Thursday: snack and dinner Friday: three full meals Saturday: three full meals

Are you able to focus by Tuesday? I feel like I would struggle to be
productive.

~~~
carlmr
You get used to it after a while. The hardest part I found was social pressure
to eat. So much of our culture revolves around eating that it's hard to do IF
with any schedule where you leave out dinner time.

So skipping breakfast is super easy (IMHO) and skipping dinner is nigh
impossible.

Skipping lunch highly depends on how pressured you feel to eat with your
colleagues. I think one meal a day (usually named OMAD) is also not hard if
you don't have lunch at work.

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Novashi
Who fasts with distilled water? Is this a thing now?

It's dangerous because it will dilute electrolyte concentrations in your body.
Drink tap/bottled water. Distilled water is completely unnatural to the body
and should only be consumed in emergencies when you literally have nothing
else. Even then it's still probably not a good idea.

There's literally no benefit to choosing distilled water over tap/bottled
water.

------
nabla9
Water-only diet is fine, but it's possible to make it unnecessarily
uncomfortable (tired and headaches)

Idiocracy was right. You need the electrolytes. In other words, you should
drink water with enough magnesium, sodium and, potassium. Many mineral waters,
zero-calorie sports-drinks and low-sodium salts like Pansalt contain the right
mix.

~~~
beoh
Indeed, it's surprising they went with distilled water exactly for this
reason.

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firasd
The two patients with most serious side-effects experienced dehydration and
hyponatremia. This supports my view that it's important to maintain
electrolyte balance during fasting (or other types of dieting like low-carb).
When doing these kinds of practices I usually add some salt to water (or other
electrolyte solutions if needed although there might be some sugar in them).

I think this should help with the common complaints they saw like headache,
fatigue, even the cardiovascular related issues. I gotta admit that as far as
'insomnia' goes I don't think electrolytes will help with that... you probably
need some combination of fat/protein/carbs to get good sleep.

~~~
meowzero
Most people who fast for more than 36 hours recommend electrolyte supplements.
Now they even have "snake juice" recipes. If fasting takes off, I bet there
will be commercial snake juice products for long term fasters.

------
buckthundaz
Yes, it is.

The better question: is it safe to eat/snack/graze chronically? Type 2
Diabetes seems to indicate it is not.

------
hourislate
I did 12 days (300 hours) on water, drinking Snake Juice off and on and seem
to be fine. I lost about 15 lbs during that fast and regained about 5-6 lbs
afterwards. I did notice my skin was a lot healthier and I felt my mind was
much stronger, everyone said I looked younger. I didn't suffer any type of
medical problems afterwards and continue to fast at least once a month for 2-4
days on just water and a daily 18/6 IF. I rarely get sick anymore (colds, sore
throats, etc). My weight has come down to a healthy level (lost 70+lbs over
the last 1.5 years).

You just have to get over the fear of not eating and understand that missing a
few meals or not eating for a few days can make you feel better. It's sort of
the same as quitting smoking, you free yourself from destructive living.

~~~
mirceal
and learn to keep your mouth shut about what you’re doing

------
lymeeducator
Fasting and duration seems to be an individual discovery, until more
scientific data measurements about amino acids, genetics, immune state,
glycogen levels, etc are established. I've water fasted over 50 times in the
15 months ranging from 16 - 48 hours to help with Lyme and other tick borne
pathogens. I've found it to be highly anti-inflammatory and have yet to feel
bad (maybe 3 very mild headaches). For example, my vision acuity improves
around 15 hours into a fast every time (noticeable when reading). I've even
jogged or walked miles 30 hours into a fast, depending on residual glycogen
levels in the blood and muscles. The glycogen should be consumed from the
liver, blood, and muscles (partial) before entering ketosis. With that said,
it's not for everyone and it is probably better to slowly increase the
duration of the water fast to evaluate individual response. Also, hundreds of
millions in the Muslim culture practice a complete daylight fast every year
with minimal side effect. That should be significantly significant ;-).

------
aedron
I would be interested in a comparison to 'total' fasting, i.e. abstaining from
both solid food and liquid. This is the most commonly practiced religious
practice (and so has a thousand year history). It would be interesting to know
what the differences were, if any.

In my own experience, somewhat unintuitively, total fasting is a lot easier
than water-only fasting. I ascribe this to the digsetive system kind of
shutting down after several hours of complete fasting. It feels like the
stomach shrivels up, and hunger pangs become fewer and further between as time
passes. Whereas going without proper food, but consuming water or small
snacks, I feel very uncomfortable and usually get a headache.

~~~
nurettin
Going for a long period of time without water is intuitively a bad idea for
your health. I think this is the reason for this study being water-only.

It also makes sense from religious perspective, since a religion will prepare
you for another life which is only attainable by dying, with no apparent
intention to give you a good and healthy life on Earth.

~~~
darkerside
Cultural evolution suggests that, regardless of intention, these practices
which have become mainstays of popular religions around the world, cover some
type of benefit to survival, reproduction, or intellectual spread.

~~~
nurettin
That, or terrible peer pressure. In my opinion, Occam's razor suggests the
latter.

~~~
darkerside
That's fine. I think it's just conventional wisdom that makes this seem like
the "simpler" solution, and I'm a bit allergic to that, but to each their own.

------
davebryand
As someone coming off a three-day water fast (five days was my max), all I can
recommend is that you try it for yourself. The lightness, clarity, and self-
assuredness that it builds is lovely.

~~~
mirceal
hahaha. that’s not healthy for you /s

seriously, as someone that has done extended fasting at times (think weeks) my
advice is not to jump into the deep end of the pool.

Try eating all your food in an 8 hour window for starters and after that do
several fasts with increasing duration s 1,2,3,5,8... days of fasting
(fibonnaci fasting)

the other thing to consider is that if you think or see something is wrong yoh
stop. fasting is mostly safe, but there are edge cases were yoh will have a
bad time.

and last piece of advice is that I have noticed people that eat sugar (lots of
sugar) have an exceptional hard time fasting (the hunger is unbearable). So
one thing to try is to kick the sugar habit before fasting (at that point even
if you decide fasting is bullshit you’ve kicked sugar to the curb and that’s
huge in its own way)

------
Timucin
Not only electrolytes but the lack of fibre is also a big problem when you
fast more than a few days.

Body needs fibre to maintain a healthy gut flora. So when the body lose the
flora, it will struggle to digest the food, take the vitamins and nutritions
from it etc. at the end of the fasting period.

This is not only something I read from articles but also something I have
experienced for a long time by the way. So please bear that in mind, keep your
gut flora healthy and your life will be easier.

~~~
Torwald
> Body needs fibre to maintain a healthy gut flora.

Do you have a good link that explains that further?

~~~
Timucin
I am on mobile, couldn’t find the original article but this one seems good
enough. Please take a look.

[https://www.scientificamerican.com/article/fiber-famished-
gu...](https://www.scientificamerican.com/article/fiber-famished-gut-microbes-
linked-to-poor-health1/)

------
AdmiralAsshat
The Chief complaints table had some interesting tidbits:

> Cancer: Breast (11), Andrologic (10), Lymphoma (3)

> Tumor: Neck (6), Breast (1), Colon (1)

So a nontrivial number of people reported _cancer_ as a side effect of water
fasting.

I suppose you'd probably want to review the standard correlation-does-not-
equal-causation fallacy, but still.

~~~
beagle3
These are the complaints and issues that brought patients to the facility that
administered the fast, not "reported as a side effect of water fasting".

> Table 1 describes chief complaint categories as total counts and as a
> percentage of total visits. A patient could have had more than one chief
> complaint per visit. Quality of life, including prevention and fatigue, was
> the primary reason patients visited TNHC (n = 384, 50%). Other major chief
> complaint categories included the cardiovascular (n = 193, 25.1%),
> musculoskeletal (n = 147, 19.1%), gastrointestinal (n = 122, 15.9%), and
> endocrine (n = 107, 13.9%) systems. Following prevention (n = 358, 46.7%),
> hypertension (n = 152, 19.7%) was the largest chief complaint category.

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projectramo
tl;dr: yes it mostly is.

~~~
davebryand
Only for Americans in labs, though. It's totally fine for the rest of the
world and our ancestors. I'm an American not in a lab and I do it all the time
with life-changing results.

~~~
projectramo
I think you think I am saying the opposite of what I think I am saying.

~~~
davebryand
Apologies, my mistake!

------
RobertRoberts
Common pharmaceuticals (even vaccines) have known (and some extremely
debilitating) side effects.

While the conclusion seems reasonable (ie, some people have adverse affects to
not eating) it's by no means a condemnation of fasting.

Fasting is the universal method of allowing the body to heal itself, animals
fast to heal naturally. (ie, no medicine actually heals only
compliments/supports healing, the body does all the real work)

~~~
fromthestart
>Fasting is the universal method of allowing the body to heal itself

This sounds like folkloric nonsense.

~~~
davebryand
When you try it for yourself, you realize that it's not.

~~~
fromthestart
That's exactly the mentality that keeps wives' tales circulating.

How often do home remedies "work" because of placebo and/or simply time?

~~~
davebryand
Ok, don't try it. :)

Wive's tales and home remedies still circulate because they often work. Of
course, you're not going to read that on Hacker News because it's biased by
people wearing modern American blinders that don't have the humility, courage,
awareness or something else, to just try for themselves. I was that way until
I tried psychedelics, meditation, pranayama breathing, lucid dreaming and many
other alternative modalities just two years ago.

All love--good luck on your journey!

~~~
fromthestart
>American blinders that don't have the humility, courage, awareness

No, it's about having some degree of scientific rigor, as opposed to blind
anecdote.

~~~
davebryand
Scientific rigor is not just about gathering people as lab subjects,
experimenting on them and publishing your findings in peer reviewed journals.
In my experience, the strongest science, where the deepest knowledge arises,
is by systematically performing experiments on yourself. This isn't possible
for all things, but it's 100% available for fasting.

Thanks for the conversation, best to you.

------
lm28469
Compared to what ?

Is it safe to eat 3 times a day + snacks, mostly over processed, calorie
dense, low micro nutrients food ?

Food is like most things, moderation/balance is key. I have no doubt fasting
can be beneficial in some cases just as I have no doubt that the typical
western diet is universally bad.

This new fasting trend is just the blowback of the over abundance / over
consumption of low quality food we experience pretty much everywhere in US /
Europe.

~~~
rfreytag
It is an NIH study which to me implies rigor; including controls.

~~~
pbhjpbhj
The report appears rigorous, but it notes in several places that the data is
not acquired in a rigorous way as it was not intended to be used to make such
assessments.

As to controls:

>"the relative safety of water-only fasting is necessarily descriptive in
nature as we did not identify a comparison group(s)"

It's a good paper.

I was left wondering why people attended the facility. A 9 day water only
fast, with limited activity, sounds pretty extreme for a 70+ yo.

~~~
shiven
[https://en.m.wikipedia.org/wiki/Sallekhana](https://en.m.wikipedia.org/wiki/Sallekhana)

