
Effects of Intermittent Fasting on Health, Aging, and Disease [pdf] - SQL2219
https://www.gwern.net/docs/longevity/2019-decabo.pdf
======
adamqureshi
I was diagnosed with pre-diabetes. I have been on the intermittent fasting
thing for about 6 months. I started with 14 hours then 16 hours and now 18-20
hour fast. I dropped 10 pounds. I have a history of diabetes in my family. I
took the 28andME DNA test and it said i have a predisposition to diabetes. The
doc said to me. You have pre-diabetes just continue to workout and watch what
you eat and your insurance does not cover a dietician and then that was it. It
was VERY HARD to not eat in morning (black coffee) and after 1 month i got
used to , it was very hard to skip lunch and after a few weeks i got used to
that. Now now my feeding window is 4pm-8pm. I was pigging out at 4pm but have
learned to control that. I workout in a fasted stated 12-1pm ( body weight ,
pullups. push-ups. 1 mile sprint HIIT and planks) I still get hunger pangs
around 3pm its as if my body is getting ready to feed / knows food is coming
around 4pm. Another thing that has happened is water tastes "sweeter" very
unusual to actually taste water. The result for me is EVERYTHING has improved.
I am 48 years old. No more carb fog. No more headaches. I think, i don't know
buy i have this clarity i think my eye site has improved too. I mean Im still
experimenting but i just feel fantastic. I will be getting blood work done
again soon. It's working for me , i don't know if it will work for others. I
tell everyone about it. Good LUCKY! :-)

~~~
300bps
How was your diet before you started intermittent fasting? When I read
anecdotal accounts like this, I often wonder if your previous diet was so poor
that doing anything to change it would've made it better.

In other words, without a control group that switched from high carb to low
carb without intermittent fasting it's hard to know if the benefits you've
seen are from intermittent fasting or just from eating better generally.

You and I are about the same age and I've been the same weight the past 30
years. I know what you mean about non-sweet things tasting sweeter - I gave up
obvious refined sugar about 6 years ago and the bag of plain raw vegetables I
eat every day for a snack tastes amazing.

~~~
adamqureshi
I was a long distance runner from like 25-36. I ate whatever i wanted. You
know what they tell you, Carb loading etc… Then i went through a vegetarian
phase. A paleo phase , An atkins phase etc... Then i went through broke phase
at 39. I really didn't get the pre-diabetes diagnosis until after 46. I
stopped the long distance running and shifted to a more of a calisthenics
workout. Pull ups and HIIT training more functional muscle type stuff , ( 2
mile run consisting of sprinting then pull ups / push ups / dips. After the
DNA test and the pre-disposition to diabetes after 45 i went to the doctor got
blood work and thats when the doctor said my AC1 is high and Im pre-diabetic.
I ate a LOT of choc-chip cookies in youth ( lol) and LOVED me a good brownie a
la mode with a LOT of fudge . Now after this IF diet and the predisposition to
diabetes and had to give up all that. This IF diet is working great for me
now. Hopefully i can stay with it. I have dropped weight but do not want to be
below 165. I think the ideal weight for me is around 170 lbs. I suggest
everyone at LEAST give it a shot and get a 23andME test as you get older to
find out if you have a pre-disposition. Then take some action or you will be
on meds. Doctor never prescribed IF to me they don’t have time for it. Doctor
never prescribed cross fit either. They just prescribe meds.

------
Gatsky
Intermittent fasting has a nice advantage - nobody can make any money off of
it. This gives it an inherent legitimacy. Contrast all other fad diets, and
essentially every supplement ever sold.

~~~
agumonkey
Surely people can make money around it. You cannot sell a void [0] but you can
very effectively sell void consulting and magazines.

[0] even this is debatable

~~~
Gatsky
I was brainstorming with a friend about creating an alternative social
environment to replace restaurants for fasters, but couldn't come up with any
good ideas.

~~~
coldtea
We call the cafes. They can serve coffee, tea, etc, have people talk, listen
to music, etc.

~~~
tabula
I’d love to see a cafe (in my area at least) with a very social “hacker” vibe.
Used books on all walls, electronic parts to build with, chess sets, events
and meetups. A place a kid could come with $15 bucks and find a good tutor
maybe (corkboard for community postings, jobs, clubs)

I was reading about how back in the day original coffee houses were a meeting
place for socialites and thinkers alike to share ideas. I’d love to see that
sense of community nowadays,I feel like it’s missing in the US and would be
celebrated, but maybe it’s just my nerdy idealization.

~~~
coldtea
> _I was reading about how back in the day original coffee houses were a
> meeting place for socialites and thinkers alike to share ideas._

Some still are in Europe at least. But they're closing down here as victims of
modern lifestyles. We had (until the 80s) 4-5 cafes here where everybody who
was everybody in culture frequented -- including different generations (20+ to
70+ year old people).

Some problems:

1) real estate prices in city center makes it impossible to keep renting for
such a purpose or (if the cafe owner also owns the building) more profitable
to sell the place and have it be made into a clothes shop or similar.

2) rising rents or (in other cases) deterioration of city centers, means that
many intellectuals, playwrights, musicians, writers, academics, etc chose to
move in other neighbours, which makes it more difficult (especially with added
traffic) to frequent the same city center cafe anymore.

3) some owners just die and their kids are either clueless and turn the place
into some "trendy" BS losing the clientele, or want to sell it and move on, or
they simply don't have kids to pass it on, and nobody gets the legacy they've
created (though sometimes new people step it who respect the original vision
-- sometimes even after a few years of the shop being closed).

~~~
tabula
Yeah that makes perfect sense, it is a bit sad to hear that even Europe is
losing this part of the culture. We change with the times, of course... I do
agree with your point about influencers moving out of city centers and towards
more affluent suburbs, it would be interesting to see if there is a market for
this after all closer to these areas. Nowadays as you said though, it’s not
likely the ROI would surpass that of a retail location or well established
franchise sadly.

------
monkmartinez
Anecdote:

I tried intermittent fasting for 11 months with very, very little to show for
it. I did the 18 hours off and 6 hours of eating plan. I have also tried a
strict vegetarian diet for 6 months with no real changes in blood work. My
Cholesterol didn't move to the dismay of my PCP and myself quite frankly.

Biology: I am a professional Firefighter that ran 1000 miles and bicycled 250
miles during this time frame. My sleep isn't always consistent which may have
played a role due to my profession. I also drink two beers (Karmeliet, Chimay
are stocked in my house) with dinner when I am off. So I drink roughly 8 - 10
beers a week. I probably could do better with calorie counting, but frankly it
seems futile so long as I like the way I look naked, lol.

~~~
fouc
Have you also tried going a whole day without eating, say 8pm as your last
meal and then no eating until 2 days later at 8am, basically 36 hours.

Doing that once a week or so is pretty effective. There's a whole host of
benefits to longer fasts as well. Helps so much with appetite control, resets
your hormones, plus autophagy, etc.

~~~
chandraonline
Totally this. Of course Anecdata etc etc. I lost almost 40 lbs this year with
5-2 and exercise 3-4 times a week and have been able to maintain my goal
weight doing 6-1. I don't eat anything crazy when I am eating. Just less carbs
and more protein. I am also vegetarian.

~~~
Moodles
How do you know it wasn’t just the exercise and fewer calories?

~~~
DennisP
I guess they don't know for sure, but from the OP:

> Intermittent fasting seems to confer health benefits to a greater extent
> than can be attributed just to a reduction in caloric intake.

------
joelrunyon
If people are interested in learning more about fasting, I put together a few
visual guides on it here - [http://impossiblehq.com/nutrition/intermittent-
fasting](http://impossiblehq.com/nutrition/intermittent-fasting)

I also highly recommend the zero fasting app for tracking. Super simple and
really clean app that makes tracking fasts simple.

Start small and see how it goes. I find the 16/8 routine tends to work best
for me personally with 36 hour fasts sprinkled in every couple weeks.

~~~
everdev
Do you find that you're able to do cognitively demanding tasks while fasting?

Even small fasts seem to sap my concentration and critical thinking. Once I
eat again I feel like I think better.

~~~
losteric
Mental clarity is a challenge when fasting on an otherwise stereotypical
American diet... those blood glucose swings are no joke.

However I have no problems on keto, or even just a consistently low-GI low-
carb diet. If anything, fasting seems to improve my discipline and "depth-
first" thinking.

~~~
VeninVidiaVicii
Interesting. I did an "animal-product only" diet for about six months, and I
began to feel sorry for everyone else and their inability to think deeply. I
was in an almost constant state of enlightenment. Then my buds convinced me to
go on a 2000 mile road trip, and after the first stop at Wendy's I lost it,
and haven't had the will to go back. It's been like 4 years now.

~~~
ChrisCinelli
animal-product only ? No veggies?

~~~
coldtea
[https://www.healthline.com/nutrition/carnivore-
diet](https://www.healthline.com/nutrition/carnivore-diet)

------
acconrad
Please understand that everyone's body is different.

What works for you may not work for someone else.

This is SO important in nutritional research because in every single one these
threads there is always someone who will say X worked for me and someone else
who says X didn't work for me. And BOTH are right.

Example:

I've done IF for years as a competitive bodybuilder and powerlifter. I've
gained and lost weight on IF. IF should (until more research is done) simply
be viewed as a compliance tactic. In other words, if it helps you eat
healthier and maintain a healthy weight: great! If not, don't assume you're
missing out on some magical panacea of health and vitality.

Recently I stopped doing IF and eating more frequently for performance reasons
so I can reach the national circuit in powerlifting. My blood work is still
fine. My weight is still fine. Again, YMMV.

------
ve55
I've been engaging in intermittent fasting to various extents for almost a
decade now and am a huge fan of it.

It takes a bit to get used to and should be adapted to over time, but I very
much love the feeling of fasting for short periods and the freedom I'm granted
to be able to easily skip meals, most commonly breakfast and lunch. I often
only eat one meal a day, which saves me time, energy, and money, but I also
enjoy the meal more, as I can include large portions of a lot of food groups
in my single meal.

That this has many potential health benefits makes this style of eating appear
even more appealing. Caloric restriction, although not quite the same as
intermittent fasting, does appear to be one of the more promising methods we
already have to help promote human longevity.

------
dpau
This is linked on gwern.net, the full article with a lot more links here:
[https://www.gwern.net/intermittent-
fasting](https://www.gwern.net/intermittent-fasting)

~~~
gwern
I didn't write OP, I just host it. And that particular page is also just some
random notes I've taken on IF over the years, and not particularly
comprehensive or high-quality.

------
ropiwqefjnpoa
From my personal experience over the past 2 years, intermittent fasting is
great. It doesn't help me lose weight, but I am able to keep off about 80% of
the weight I lose when I do a keto diet every few months.

------
jl2718
I’ve been doing some form of intermittent fasting for a large part of the last
15 years.

I started with 36 hours once a week because I made money based on the
appearance of my body. It works tremendously well in the short-term, but it’s
deceptive. The tissue loss is mostly fat, which looks great, but there is
definitely some muscle loss, which is an order of magnitude harder to gain
back, so the long-term effect is muscle wasting and fat rebound as caloric
demands drop. It’s easy to see in my photos. Later I did OMAD several times
for stretches of about a year with roughly similar short and long-term
effects. Recently I completed a 100-hour fast.

There are a few basic issues. First, with IF you’re not really fasting as long
as you think you are. Small intestines take about 6 hours, and the colon turns
fIber into MCTs for days. Second, the insulin surge becomes preferential to
fatty acid storage over muscle glycogen. Third, you lose the ghrelin-induced
GH that releases fatty acids throughout the day to feed the muscles. There may
be autophagy benefits, but that may be as true for satellite cells as it is
for cancer, and maybe more so because cancer usually originates in fatty
tissues with lots of energy nearby.

At this point, by experience and by science, I don’t think IF is the best diet
protocol if you have the discipline for a more continuous protocol. I don’t,
so I can’t say I’ve tried that, and I hate the fat on my body, so I’m not sure
where to go from here. I’m not 100% convinced either way, but I wanted to give
a balancing perspective.

------
efiecho
I have been intermittent fasting for about 23 hours a day in the last decade
and this works very well for me, I couldn't imagine to eat more often than
that.

However, for the first seven months of 2019 I tried to do 48-72 hour fasts
three times every week, but I just couldn't adapt to that. It's nice with the
euphoria effect, but in the long run I found it depressing going to sleep
without eating and it had a very negative effect on my life quality.

Now I'm back at eating a single meal every day and feel great.

~~~
flippyhead
Once I realized that I was simply addicted to food, and that hunger was simply
a withdrawal signal, it made it a lot easier to accept that signal as simply
useful information instead of something that was necessarily uncomfortable (to
be fair, I consider being cold and other such signals in a similar light). Now
I rather enjoy being hungry, knowing there will be a brief hump to traverse
before my body replies with a number of favorable responses.

When traveling or over the holidays I realize I'm eating over longer periods I
really notice how much less I like it now. I only do it because of basic,
maladapted pleasure seeking behavior.

~~~
thejackgoode
"withdrawal signal" is a very precise way to phrase it

------
roystonvassey
[https://telegra.ph/My-experiment-with-IF-03-09](https://telegra.ph/My-
experiment-with-IF-03-09)

A good time and place to plug results of the IF experiment I did a few years
back. FWIW, I have been on a no-breakfast, no-lunch protocol, on weekdays
since then and I absolutely love it because it keeps me sharp through the day
(no post-glucose “dullness”).

~~~
sytelus
This is a good experiment although you haven’t mentioned how you eat when
breaking the fast. It seems a lot of advantages of IF will be suppressed if
you continue consuming refined carbs during eating window. I am interested in
IF setting where you consume same calories during eating window but only
through ketogenic diet.

~~~
roystonvassey
Thanks! Yes, I can imagine that that hypothesis would hold true and probably
contributed to a higher fat loss. But, like I mentioned, I was keen to isolate
<i>only</i> the fasting effect, without controlling for the diet.

------
torgian
I’ve been doing small fasts: typically in the morning, I don’t eat anything
until after I work out. So, these usually end up being twelve to 16 hour
fasts.

I would actually like to try to fast for 24 hours, starting after an evening
meal.

My problem is I do a lot of cycling. If I don’t eat, I bonk hard and lose
energy. So, I would need to time this after a day of resting after a ride.

~~~
TrueGeek
How long are your rides? For rides around an hour to an hour and a half I can
ride while fasting, even at the end of an 18 hour fast. The trick is to just
work up to it.

~~~
torgian
Up to 50k there’s no problems. But, above 50k I’m gonna end up emptying my
glycogen storage.

~~~
609venezia
You might enjoy Attia on distance cycling while in nutritional ketosis:
[https://peterattiamd.com/ketones-carbohydrates-can-co-
exist/](https://peterattiamd.com/ketones-carbohydrates-can-co-exist/)

(like you, he eats carbs when riding long distances--even with the aim of
staying in ketosis)

~~~
torgian
This was a very interesting read. I’ve never gotten this in depth with my
nutrition before. I’m beginning to think I might want to look more into a keto
style diet.

I eat a lot of carbs ( mostly clean, veges and fruits ) and cook most of my
food at home. I’ve been maintaining weight but haven’t really lost much fat.

I know my diet is the reason, so the answer is probably to reduce carbs and
increase the proteins. Perhaps try for a longer intermittent fast.

~~~
jl2718
Listen to the latest Peter Attia podcast. Short answer for weight loss is to
stay in zone 2, eat small amounts of carbs only during zone 2+ exercise, only
enough for non-insulin-dependent GLUT4 transport. You can roughly double your
fatty acid metabolism in a few months like this.

------
mrfusion
I’d like to fast until lunch time but I haven’t found any substitute for milk
in coffee and I fear that breaks any fasting benefits.

~~~
ivan_ah
Same problem here. I'm also confused because some sources say coffee (black)
is OK during fasting, but I've also heard that even black coffee "wakes up"
the metabolism enough to lose the benefits.

Could someone who knows about this comment or post links to info: is black
coffee during fasting periods OK?

~~~
thatcat
There needs to be something with calories to metabolize to end a fasting
period, coffee has low/no calories, you can have up to a fifty calories before
the fasting is broken. Caffeine is metabolized, but has no caloric value so I
don't think it would count.

[https://jamesclear.com/reader-mailbag-intermittent-
fasting](https://jamesclear.com/reader-mailbag-intermittent-fasting)

------
troydavis
Related reading:

* “System-wide Benefits of Intermeal Fasting by Autophagy“: [https://www.cell.com/cell-metabolism/pdf/S1550-4131(17)30608...](https://www.cell.com/cell-metabolism/pdf/S1550-4131\(17\)30608-3.pdf)

> We established an isocaloric twice-a-day (ITAD) feeding model wherein ITAD-
> fed mice consume the same food amount as ad libitum controls but at two
> short windows early and late in the diurnal cycle. We hypothesized that ITAD
> feeding will provide two intervals of intermeal fasting per circadian period
> and induce autophagy. We show that ITAD feeding modifies circadian autophagy
> and glucose/lipid metabolism that correlate with feeding-driven changes in
> circulating insulin. ITAD feeding decreases adiposity and, unlike CR,
> enhances muscle mass. ITAD feeding drives energy expenditure, lowers lipid
> levels, suppresses gluconeogenesis, and prevents age/obesity-associated
> metabolic defects. Using liver-, adipose-, myogenic-, and
> proopiomelanocortin neuron-specific autophagy-null mice, we mapped the
> contribution of tissue-specific autophagy to system-wide benefits of ITAD
> feeding. Our studies suggest that consuming two meals a day without CR could
> prevent the metabolic syndrome.

* “Short-term fasting induces profound neuronal autophagy“: [https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3106288/](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3106288/)

> We first validate the approach by showing that it allows the identification
> and characterization of autophagosomes in the livers of food-restricted
> mice. We use the method to identify constitutive autophagosomes in cortical
> neurons and Purkinje cells, and we show that short-term fasting leads to a
> dramatic upregulation in neuronal autophagy.

> …

> Our data lead us to speculate that sporadic fasting might represent a
> simple, safe and inexpensive means to promote this potentially therapeutic
> neuronal response.

------
laplacesdemon48
Are there any active studies on intermittent fasting in healthy young adults?
(NY area)

I’m interested in intermittent fasting but I’d like to objectively track the
effects beyond fat/weight loss. For example: ketone body blood concentration,
respiratory exchange ratio, heart rate variability, etc.

I couldn’t find anything here but maybe I’m not looking in the right place:
[https://clinicaltrials.gov/ct2/results?term=intermittent+fas...](https://clinicaltrials.gov/ct2/results?term=intermittent+fasting&Search=Apply&recrs=a&age_v=&gndr=&type=&rslt=)

------
yellow_lead
> _Epidemiologic data suggest that excessive energy intake, particularly in
> midlife, increases the risks of stroke, Alzheimer’s disease, and Parkinson’s
> disease._

Would be great to have some new therapies for these terrible diseases.

------
zxcb1
Are there any comparable studies taking into account the gut microbiome?

------
mark_l_watson
I agree with the advice here to start slowly. I am not fasting right now
because I am on the Dr. Fuhrman Eat to Live anti inflammatory diet, but
usually I try to eat all my food on a given day in 8 to 9 hours, which leaves
16 to 15 hours a day fasting. Every few weeks, I like to get a one day fast
in, but I am not always consistent with that.

By starting slowly, and by eating plenty of food during the eating periods, it
is fairly easy to maintain energy during fasting.

------
alexmingoia
Slate Star Codex published an article investigating whether intermittent
fasting extends lifespan, and found that the research is flawed:
[https://slatestarcodex.com/2019/12/12/acc-does-calorie-
restr...](https://slatestarcodex.com/2019/12/12/acc-does-calorie-restriction-
slow-aging/)

~~~
toasterlovin
Luckily, whether intermittent fasting will work for you is really easy to test
with an N = 1 study where you are the 1.

~~~
troydavis
> whether intermittent fasting will work for you is really easy to test

This is only true for people who have something they want to change. In
practice that basically means weight or a biomarker that’s practical to
measure, like fasting blood glucose. For people with normal weight and insulin
response, the possible IF benefits seen in mice are difficult or impossible to
measure. For example, identifying autophagy in a standard CBC with diff is
experimental at best
([https://pdfs.semanticscholar.org/08a3/bf79055d69da0fe7305255...](https://pdfs.semanticscholar.org/08a3/bf79055d69da0fe7305255bf3c8a72438d1a.pdf)).

------
troydavis
If anyone has done this without trying or wanting to lose weight (ie, for some
other purpose), could you share more? What was your goal? Did you reach it?
For 24+ hour fasts, did you deliberately compensate by eating more before and
after?

~~~
matwood
I started IF with the plan of simply trying to be healthier. I'm big into
fitness and read that even at the same calorie levels, there was a study where
people who IF got leaner while staying around the same weight. So with those
two items in mind I decided to give it a try a couple of years ago.

For me, skipping breakfast ended up meaning less calories overall. I did lose
some weight, but in a good way. My lifting/cycling/jiu-jitsu training were all
positively impacted mainly because I was leaner.

I used to be a person who woke up hungry and would immediately eat breakfast.
Now hunger isn't really something I notice. Sometimes it will be early
afternoon before I think about eating.

I learned a lot about my personal nutrition. If I eat poorly the day before, I
notice more hunger the next day during IF. Experiencing this feedback loop
helps to re-enforce to not eat poorly even during an eating window.

So, I hit my two initial goals and will continue to use IF for the ongoing
health benefits (anti-inflammation). My weight stabilized ~10 pounds less from
where I started, but I did not lose much if any muscle.

------
gtt
Too bad, there is no abstract in the paper.

~~~
xtracto
>Animal models show that intermittent fasting improves health throughout the
life span, whereas clinical studies have mainly involved relatively short-
term interventions, over a period of months.

> It remains to be determined whether people can maintain intermittent fasting
> for years and potentially accrue the benefits seen in animal models.
> Furthermore, clinical studies have focused mainly on overweight young and
> middle-age adults, and we cannot generalize to other age groups the benefits
> and safety of intermittent fasting that have been observed in these studies.

Conclusion is always a good type of abstract.

------
sfgweilr4f
Old-style 8 hour eating window but slightly shortened. 16 hour non-eating.
Simple.

FWIW I used to do the 12 hour thing. Breakfast at 7. Dinner at 7. Lunch in
between. Ditched that and went down to 6-8 hour instead. I've found I can
actually do 4 hour eating window but that's irritating for reasons other than
hunger/satiety.

------
antisocial
IF is the only diet I can follow, I have been on it for three years, I think I
am going to do it for life.

I am not affiliated with it, but check out idmcommunity.idmprogram.com/

Also, Dr. Jason Fung is an authority on IF, if you want to check out his
videos on YouTube.

~~~
thatcat
that link doesn't work, idmcommunity.com redirects to thefastingmethod.com
now.

------
shortandsweet
Will it help with gout?

~~~
radnam
From my N=1 experience, it has not helped me.

------
chktts
This is just called skipping breakfast. But I guess there was a need for a new
fancy term for an old thing.

~~~
Angostura
Except it isn’t. It also involves not eating or snacking after early evening.
It is, what it says.

~~~
thegabriele
For many people there's no snacking or eating outside regular meals
(breakfast, lunch, dinner). In this case 16/8 IF would be skipping breakfast
which is exactly my case for many years now.

~~~
coldtea
> _For many people there 's no snacking or eating outside regular meals_

Just not many people in the US...

~~~
Ididntdothis
Unfortunately the rest of the world is catching up quickly.

~~~
coldtea
True. It's not the US per se, it's the processed food (crap) industry and the
work lifestyle (no time to cook).

------
5cott0
intermittent fasting is an eating disorder

------
paulcole
Has there been any research into the effects of nightly 6-8 hour fasts? I know
this is just an N=1 anecdote but I’ve been on this plan for 35+ years and have
nothing but positive things to say about it.

