
A Guide to Intermittent Fasting - hunglee2
https://www.stedavies.com/intermittent-fasting/
======
bmcusick
"Calorie restriction is proven to help you live a longer life."

This is essentially false for anyone reading the article. The studies that
showed mice living longer lives from calorie restriction were restricted _from
birth_ , and thus their growth was stunted, and smaller creatures live longer
(think about dogs; big ones die earlier).

Studies of animals where the calories restriction was started mid-life all
show increased mortality. The immune system and wound healing are compromised.

That being said, I've been using a system basically like Leangains since March
for the purpose of losing weight. It's just cutting calories and I find that
two meals a day plus a big plate of vegetables for dinner allows me to fast
from Noon to breakfast the next day with minimal hunger.

But this is a calorie deficit/weight loss strategy because I'm overweight, not
a lifestyle thing I'm going to keep up forever. And so far I've lost 29 lbs
since March, so that's nice.

There are benefits to fasting occasionally I think, but that's not calorie
restriction. It's just giving your body a 24 hr period to engage in autophagy
and clear out some of the junk; you make up the calories on the other days.

~~~
nxsynonym
"It's just giving your body a 24 hr period to engage in autophagy and clear
out some of the junk; you make up the calories on the other days."

Very true. People don't realize that calories don't "reset' after the day
ends. Net calorie gain/loss is best measure on a weekly or bi-weekly basis. If
you stay under target for 3 days then binge two full pizzas, you aren't
actually going to lose anything.

~~~
buserror
That's not exactly true, if you actually _fast_ for 3 days, even two pizzas
won't make up for the lost calories of a 3 days fast, and it's very likely
won't be able to eat 2 pizzas in one go..

I know, I fast regularly (I'm days 2 of a 5 day one at the minute) and I do
eat quite a lot when I'm not fasting, and despite what everyone will tell you,
I don't 'put back the weight immediately' \-- even if I have a nice binge
dinner on day 5.

In fact, after quite a few years of fasting very intermittently (I do perhaps
4 a year), I know I can't eat as much as I used to, and I don't 'creep' up as
I used to when I started. I'm a LOT dryer than I was, and I can still enjoy a
32 ounce steak (!) when I feel like one.

~~~
nxsynonym
True, but this article is in reference to IF, not extended fasting. Generally
IF is done daily, with a feeding window of 8-10 hours and the other 14-16 are
for fasting.

Not many people incorporate 2-3 day fasts into their diet.

------
m00x
I'm a big fan of intermittent fasting, but this article lacks any kind of
proof on many of the cited benefits:

> Benefit #2. It helps with calorie restriction

No study cited that proves this. Only cites studies about the benefits of
"proof" that caloric restriction helps longevity, but really is just a
correlation.

> Benefit #3. It helps you lose weight and body fat

No study cited, follows up with "believe me, it worked on me".

Cites this study: "Alternate day calorie restriction improves clinical
findings and reduces markers of oxidative stress and inflammation in
overweight adults with moderate asthma."

That's incredibly specific and shouldn't be generalized to the general
population.

>Benefit #5. It helps your cells clean and repair themselves

Cites studies made on rats/mice. Although that's a good indicator it _might_
be mirrored in humans, it proves nothing.

> Benefit #7. It regenerates the immune system

Study was made on 3 day fasts, and not intermittent fasting.

It would nice if he pointed out those are potential benefits instead.

~~~
ktRolster
I've found there is one very real benefit of fasting: it makes food taste
better.

~~~
nicolashahn
If it tastes better because of your appetite, then that's basically just
sacrificing some pleasure of not being hungry for the pleasure of the taste of
food, like hitting your head against a wall because it feels so good when you
stop.

(disclaimer: I practice IF but take issue with this one claim, at least
without the stipulation of hunger)

~~~
wahern
If you fast for several days, by about the 3rd or 4th day your sense of smell
becomes much more sensitive. It's an interesting and memorable experience--
almost like developing a super power--but for some reason whenever I describe
this experience to people they don't seem to put it in the "pro" column.

~~~
buserror
I do the same, and I experience the same. In fact I find what the OP propose
of the 'skipping breakfast' to be the worst effort/benefits fasting method.
The first day of a multi-day fast is always the hardest, after that it get a
lot easier, and you get these benefits.

I also get a mental 'high' on day 3+4, but it goes down after that.

------
lolc
Intermittent fasting may be good, but factual errors in this piece made me
stop reading further. It seems the author didn't study the topic well enough
to write about it.

Others have already pointed out dubious claims about increased longevity. I'll
take issue with section "Benefit #1. It supports with hormone regulation and
lowers diabetes II risk." Sure eating less carbohydrates will lower your
diabetes risk. But that doesn't mean you have to fast, just that you should
eat less carbohydrates.

And contrary to what is written under that heading, insulin lowers high sugar
levels, it does not cause them. High insulin levels are caused by high blood
sugar. While it is plausible that fasting will lower your risk of diabetes,
that's foremost because you're eating less and thus the glycemic load is
lower. (Glycemic load is how much your blood sugar rises from food.) You can
lessen the load by eating less in quantity or by refining carbohydrates less
(by eating fruits instead of drinking juice, for example)

While I think that fasting is a valid and rather easy way of countering
unhealthy eating habits, it is just one of many possible ways.

And this is no myth: "If you go too long without food your body will start
eating itself (muscle)". The article lists this together with other myths, as
if starvation weren't a real danger. Sure most people won't get any ill
effects from not eating for a day (it's healthy for most) but once the fat is
gone, muscle is next.

------
bykovich2
"Calorie restriction is proven to help you live a longer life."

Flatly untrue. The article linked to "in proof" is about primate studies that
suggest -- perhaps even strongly suggest -- that caloric restriction can slow
the process of aging. This does not, however, rise to the level of proof, and
certainly does not provide conclusive indication of what caloric restricters
can expect more generally. The author is apparently willing to make this
grandiose claim to a susceptible audience with nary a word about its
limitations, which should set our alarm bells ringing.

If you want to calorically restrict, do it because you've thought long and
hard about the consequences of a truly significant choice -- not because it's
a tech industry fad.

~~~
HorizonXP
I think the phenomenon is poorly understood and studied, but it's likely not
the calorie restriction itself, like you claim.

Apparently it has to do with autophagy
([https://en.wikipedia.org/wiki/Autophagy](https://en.wikipedia.org/wiki/Autophagy)),
which your body seems to enter when you restrict calories. IF apparently
stimulates your body to perform autophagy due to the fact that you're timing
your meals.

TBH, I still need to do my own research to see how much of this is real vs.
pseudoscience, but I've noticed an improvement to my health. Whether that's
placebo effect or not, remains to be seen.

~~~
allover
Well GPP is just saying that 'calorie restriction' is not proven to 'help you
live a longer life', irrespective of the IF context.

As for IF, as you say, it is basically not proven to do anything (no
'phenomenon' at all). Simplest and most logical reason for success is because
it helps people stick to their diet, by arbitrarily restricting the window of
eating.

Opinion I read on r/leangains is that some people find it easier to e.g. just
eat two 600-800 calorie meals within their IF window, rather than sticking to
a diet that involves 3-4 smaller ~300-400 calorie meals, spread out through
the day, none of which feel 'satisfying'.

------
wdewind
Overall the body is pretty good at nutrient partitioning and maintaining a
caloric balance. There may be small statistically different outcomes for
practicing stuff like IF, but there aren't clinically different outcomes
_outside of using IF to maintain compliance to a diet._

If IF helps you maintain your ability to comply to the diet you want, great,
but there's absolutely no evidence for it being superior than the same diet
spread over the day, and there a few ways in which it's probably suboptimal,
like building muscle (although again not hugely so, so compliance probably
trumps the small advantage you get).

~~~
jraby3
What about in controlling insulin resistance? I thought the data was pretty
strong in favor of IF helping significantly.

~~~
wdewind
It's not. The same amount of glycemic load consumed all at once or over time
throughout the day will not have a significant effect on insulin resistance.
Not being able to eat as much because you are constrained to an 8 hour window
will cause your overall glycemic load to go down.

------
nsxwolf
Even if IF is nothing more than calorie restriction supporting the calories
in/calories out hypothesis, it succeeds in creating a real psychological
benefit - you get to have real, satisfying meals of food you actually like -
you just have to wait longer for it.

If you're trying to lose weight, and you like food, the sight of the food in
these 1200 calorie 3 meal daily plans is incredibly depressing. Eating an egg
white on a piece of wheat toast every morning for the rest of your life is a
kind of torture that never gets easier. It's like trying not to blink forever,
or holding your breath forever.

Much better to just wait all day and spend the calories on a generous portion
of something you really want to eat.

~~~
agumonkey
I'm aiming at this these days. I'm cutting most shitty food (I allow some
pastry in the week; but no soda, no fast food, no industrial meals). But I'm
not mentally ready to cut the pleasure of a good meal. I'll better stop using
my car and job between places and keep higher calories. I "believe" the
benefits of good ingredients, close to no fat and no added sugar + regular
sport is already significant. Later I'll move to more vegetables, less
carbohydrates to trim my body fat even further.

~~~
majewsky
> I'll better stop using my car and job between places

I suppose you mean "jog", but jobbing between places sounds very intense as
well. :)

~~~
agumonkey
Indeed, keyboard slip.

------
HorizonXP
I have been doing intermittent fasting (IF) on a 16/8 or 18/6 schedule for the
last 6 weeks. In combination with keto/LCHF food, keeping my daily caloric
intake under 1550, and weight lifting 3x weekly, I've been losing 2.5 lbs/week
on average.

IF fits my lifestyle really well, since I only end up eating twice. I feel
super energetic and focused while I'm fasted, and the lack of insulin spikes
when I do eat have helped too. Besides losing weight, my overall health seems
better. Cuts and injuries heal faster, less facial acne (I didn't have a lot
to begin with though), and all of my stomach/intestinal issues are gone.

IF works really well for me, and I highly recommend that people try it for
themselves for 1-2 months, to see if it works for them too.

~~~
marksc
>I have been doing intermittent fasting (IF) on a 16/8 or 18/6 schedule for
the last 6 weeks.

What do 16/8 and 18/6 mean in this context?

~~~
seveneightn9ne
fasting hours/eating hours. So eating within an 8 or 6 hour window each day,
and fasting for the other 16 or 18

------
zamber
There's a net of dieting resorts around Poland doing "Dieta Dąbrowskiej" among
some other health-oriented stuff.

In essence it's calorie restriction on veggies for 2-6 weeks at a time
supplemented with blood tests and physical activity. She (Dąbrowska) states
that it resets the immune system, restricts cancer growth (or even puts
cancers into recession), helps with diabetes and cures food intolerance.

Proof for it is provided as "I've seen people that improved". I'm highly
skeptical about it as my vegan-celiac-fit family part got hyped for it and
went through a 3 week run. They came back with anecdotal self-healing
miracles.

The diet is around 600-700 kcal a day, low on sugar. Supposedly it stimulates
autophagy giving all of the stated benefits (on top of cleansing out
"toxins").

As a side note I found that food intolerance is in fashion recently. There's
one (!) test offered in my area for it called the Food Detective (made by
Cambridge Nutritional Sciences Ltd.). I'm highly skeptical of it too as
there's no competition and I couldn't find any studies confirming it's
effectiveness.

My main concern is the potential impact on the brain. I vaguely recall some
study observing neuron loss during extended periods of starvation.

Also having some sensible studies to back it up (or debunk it) would be nice.

~~~
reitanqild
With you on the scepticism esp. about the detox-thing.

That said fasting in some form seems to have been with us for a few thousand
years and it seems unlikely that it would be so widely documented and
practiced across cultures and religions if there wasn't _some_ benefits to it.

------
gricardo99
Could any one point me to advice/guidance, or can answer from experience, what
you would do differently when doing IF with regular exercise?

It seems to me you'd want to make some adjustments to types and amounts of
calories to account for exercise, especially anything very taxing, like
endurance training. But I haven't found any advice on this specific topic.

~~~
e59d134d
I don't have advice but my personal experience is that lifting weights is easy
but cardio is almost impossible.

I don't really fast on purpose but I mostly eat one large meal a day (dinner).
I workout in evenings before dinner.

I do snack if I get hungry maybe around 4PM. My snacks are usually Lay's
chips. Sometimes, I get a Gatorade for gym.

I can lift about as heavy as if I had a big lunch but cardio is different
story. If push myself as hard as one days when I had lunch or a lot snacks, I
will start to see stars. I go a lot slower with cardio then. (Seeing stars or
vision going white is sign of sudden drop in blood sugar level).

------
logicalmike
I've cycled through many methods of eating, trying to find an optimal diet to
pair with heavy weight training for 6-7 days a week.. while at the same time
keeping my weight more or less the same (with only slight fluctuations).

Intermittent fasting (or more specifically, following a loose version of the
Renegade Diet) is where I landed.. and have been able to keep my weight steady
while still making strength gains. In my opinion, it's a good choice who have
a hard time controlling their food intake without the hassle of counting
calories and/or macros. This way, rules are set, and then can look forward to
~4 hours of eating without restriction. I've pushed this feeding window to the
limit, and to gain significant amounts of weight week over week, I basically
had to eat until I physically sick for multiple days.

I've also had blood work done, with everything being normal since I started
over a year ago.

~~~
thrownblown
I've been playing with IF and high activity too, and have been struggling to
find a good balance.

My sport (track cycling) is very power intensive and has both strength and
endurance components.

I have two eating periods on active days and one on my rest days. That seems
to do me ok, but endurance has still been an issue.

~~~
logicalmike
It's hard to know without seeing what you eat, but are you sure it's enough?
Have you tried tracking a few days to see if you're hitting high enough
calories? I'm really stuffing myself at night.. and from others I've talked
to, it's very easy for them to under-eat.

------
siliconc0w
I find IF helpful to regulate calories. Basically I skip breakfast, eat a
light lunch around 1, and a large protein/veg heavy dinner. This is effective
if I stick to it (and I generally have for quite some time now). You can't do
IF, eat crap, and expect results. You still need a disciplined diet. For me I
found I basically need to severely restrict carbs. I will overeat carbs but
not protein/less starchy veg. Try eating a BigMac's calories in spinach. It
isn't going to happen.

As other people have mentioned, a lot of the claims made about IF aren't
entirely backed by the research. Most experiments are with mice and usually
use a more severe form of fasting that what is advocated. It's just another
way to do caloric restriction which may work better than the previous 'best
practice' of 'many small meals'.

~~~
adrianmonk
_" Basically I skip breakfast, eat a light lunch around 1, and a large
protein/veg heavy dinner."_

Apparently you are my dietary twin. I came to this exact formula accidentally,
though, as a result of calorie counting. I skipped breakfast because I could
do that most easily. Then I decided lunch would be really light because that
gave me the leeway to have a more satisfying dinner and feel completely full
once a day. And I didn't want to take the risk of having a light dinner, being
hungry, and being unable to get to sleep.

I ended up with the mix of protein- and vegetable-heavy dinner because I
started reading the nutrition labels of absolutely everything. Then without
seeking out a particular type of food, I tried to remember which foods seemed
like a good combination of filling and low calorie. And protein and vegetables
is what it ended up being.

Overall it has worked great. The types and amounts of food I eat feel normal
now, and I feel good, and my ability to control my weight has surpassed all
expectations.

------
liamcardenas
I do intermittent fasting (16/8) every day and have found immense benefits.
More specifically, I do what's called "time-restricted feeding" in which I
only eat between 7am and 2pm (so if I start eating at 10am then I can only eat
for 5 more hours). I also strategically eat in the morning because I that is
when people are most glucose sensitive.

So far I have almost lost 20lb without changing anything in my diet (I
currently am 6ft and 200lb). I did not expect this result going in, but have
been pleasantly surprised. Research shows that IF can lead to a slight weight
loss, but nothing like what I have experienced-- so I wouldn't want anyone to
think they can replicate my results. That being said, I would do this even if
I did not lose weight because the health benefits are immense.

~~~
snvzz
Been doing this for ages without intending to.

I generally eat 13-14 and again 18-19. and that's it.

------
cybervegan
I did intermittent fasting 2 days a week for 2 years (2013-2015). Initially I
lost weight, which was good. Energy levels were elevated, minor health
problems seemed to have gone away or lessened. Towards the end, I think I was
being rather too "soft" on myself, so wasn't really reaping the benefits, and
it got to be a grind. I then had some rather unpleasant emotional issues to
deal with, and found I didn't have the emotional energy to continue: I have
pretty decent willpower, but when I'm badly emotionally stressed, it crumbles.
I've been _intending_ to get back into I/F ever since, and though I'm
emotionally in a far better place, I haven't managed to muster the emotional
energy for it yet.

------
inetsee
One diet I read about recently that I found interesting is called the Fasting-
Mimicking Diet. It's not a strict fasting diet; you spend five contiguous days
per month eating a very specific diet of about 1100 calories per day. The diet
is low in carbs, low in protein and relatively high in unsaturated fat. One of
its claimed benefits is that it's easier to stay on than the other strict
fasting diets. Some of its other claimed benefits sound quite amazing.

References:
[http://sciencebulletin.org/archives/10692.html](http://sciencebulletin.org/archives/10692.html)
[http://www.bbc.com/news/health-39070183](http://www.bbc.com/news/health-39070183)

------
SuperGent
-Stop eating at 8pm (the time of my last meal) -Start eating at 1 or 2pm the following day

How is this just not just skipping breakfast? 3 times a week? I know lots of
overweight people who do this, although it is easy to follow.

~~~
majewsky
From personal experience [1], even when I have only two big meals, I'll eat a
ton of snacks of sweets during the whole day. Cutting these out is the large
difference to "just skipping breakfast".

[1] Have not done any fasting, but recently started considering intermittent
fasting.

------
KVFinn
I really like the most moderate form -- simply eat two meals a day, skipping
either your first meal in the day or your last.

Everyone 'fasts' for 8 - 12 hours just by sleeping anyway, so simply skipping
one meal nearest sleep means you fast for about 16h a day.

------
jimmcslim
Any guidance on the risks of IF for folks with Hashimoto's
Disease/hypothyroidism?

------
gxs
For the 16+8 routine, does anyone have an idea of how you're supposed to carb
cycle?

~~~
arohner
Read the leangains links elsewhere in the thread. In those, Berkham recommends
high protein,medium/high carb, low fat on weightlifting days, and high
protein, medium fat, low carb on non-weightlifting days.

------
bfred_it
Why is this stuff on HN? It reads as pseudo-science.

~~~
jo909
So we can discuss it in a constructive manner, for example by pointing out
what makes this pseudo-science and why it might be not the worst idea anyway.
Like other commenters have done, and I enjoyed reading their arguments.

