The power of intermittent fasting | Hacker News Reader

The power of intermittent fasting

bbc.co.uk

143 pointstechnology69 comments

The interesting thing about intermittent fasting is that it seems to work through a different but overlapping set of molecular mechanisms to calorie restriction. The gene expression profiles in rodents say that the way in which intermittent fasting (such as alternate day fasting, the most commonly studied mode) works to alter metabolism into a better running state is not quite the same as the mechanisms of straight calorie restriction.

http://www.fightaging.org/archives/2010/05/intermittent-fast...

http://www.fightaging.org/archives/2009/11/a-little-intermit...

So evidently you still have upregulated autophagy (i.e. better housekeeping in cells), the levels of methionine in the diet are going to be lower thus triggering that important switch in the metabolism of calorie restriction, more ghrelin floating around to stimulate the immune system, and so on. But it's not running the same way as for a steady low diet, and that appears to make some differences. Intermittent fasting is not as well studied as calorie restriction, but it is shown to extend life in mammals, and it is certainly easier to manage for most humans:

http://www.fightaging.org/archives/2009/02/practicing-interm...

Which means to say that you'll probably obtain health benefits by doing it, but the studies that show massive health gains and enormously lowered risk of age-related disease for calorie restricted humans may or may not apply to you.

Great point; I've been thinking about this for some time. Would love to have more data, though! I'm also interested in any metabolic similarity either influence has to endurance athletics.

Exercise and calorie restriction both influence autophagy. In fact pretty much everything that extends life in laboratory animals boosts autophagy one way or another - such as through altered expression levels of heat shock proteins and related regulators. You'll find that foundational study on exercise mimetic drugs looks at heat shock protein manipulation more often than not.

http://www.fightaging.org/archives/2012/01/testing-autophagy...

http://www.fightaging.org/archives/2009/09/heat-shock-protei...

http://www.fightaging.org/archives/2008/03/all-roads-lead-to...

There is no consensus on whether different types of aerobic exercise are better or worse for longevity, or whether more than the modest 30 minutes a day is better or worse for longevity. Elite athletes have a massive longevity advantage over the rest of the population, for example, but that can just as well be explained by the fact that you have to be robust to become an elite athlete in the first place.

http://www.fightaging.org/archives/2011/05/putting-upper-bou...

Exercise also works through hormesis and reactive oxygen species signaling - which is why flooding your system with ingested antioxidants can destroy some of its benefits:

http://www.fightaging.org/archives/2009/05/exercise-reactive...

Where are you based? Would love to host you, Cynthia Kenyon, and my friend Laura Deming for a dinner on aging research.

We do weekly salons here: thesprouts.com

Intermittent fasting works for me: http://chester.id.au/2012/04/17/my-diet/

I love food. I love everything about it. I love the smell of it, the sight of it, the way steam rises of freshly cooked food. I love mixing it up. I love the act of chewing, the taste, the way it feels in my mouth. The act of swallowing is great and the sensation of fullness is sensational.

So it should come as no surprise that for me, at least, weight control through portion control has been an absolute failure.

What has worked for me is skipping meals altogether. If I don't start eating at a given meal time I don't have to stop.

These days I skip breakfast, have a simple meal-replacement of my own recipe at lunch, train in the afternoon and eat whatever I feel like at dinner. So far I am 24kg (~53lb) down from my peak weight and the trendline is still pointing down.

(I wrote about that, too: http://chester.id.au/2012/05/26/fat-and-simple/ -- it caused one hell of a ruckus)

But do you know why? It isn't the schedule that really matters. It's that I imposed a caloric deficit in a way that I personally am I able to sustain. For others it might be low-carb or eating every 4 hours or being a vegetarian. Whatever. At the end of the forcing function of weight control is how much you ate.

Once I reach a weight I'm happy with I'll probably just eat an ordinary lunch more often.

>But do you know why? It isn't the schedule that really matters.

You haven't shown that. Where's the randomized experiment where one group is assigned to eat 3000 cal/day evenly distributed, and the other group is assigned 6000 cal during an 8 hour window, every other day, and then the same thing but now 1800 cal per day, or 3600 every other day?

I don't fully understand this compulsion to explain anything successful in the weight-loss field, ultimatlely, in terms of calorie restriction.

> I don't fully understand this compulsion to explain anything successful in the weight-loss field, ultimatlely, in terms of calorie restriction.

Because any other hypothesis has to explain why it violates the conservation of energy and matter. (Also: such studies are harder than they look to arrange. Completely controlling someone's caloric intake and output is difficult to achieve).

What tends to happen in discussions such as these is that they devolve into a shouting match about the boundaries of causality. In a basic physical sense, caloric balance is the only thing that matters. It is the causal element. Cut calories enough, you will lose weight. Raise them enough, you will gain. The relationship won't be linear, immediate, proportional or unary. But it will be causal.

But that's oversimplifying! comes the cry. And it is. The internal mechanisms of the body mediate and modulate weight control in interesting ways. The ever-plunging $:calorie ratio has its input. And so on and so forth, ad infinitum.

Proponents of IF talk about various interesting biological pathways that turn on and off, hormone levels that change and so on. But the direct cause of weight loss in IF is that you simply do not eat as much. You can't, you've removed entire culturally-important, structured opportunities to eat. Gone, just like that.

> > I don't fully understand this compulsion to explain anything successful in the weight-loss field, ultimatlely, in terms of calorie restriction.

> Because any other hypothesis has to explain why it violates the conservation of energy and matter.

Umm, no. None of the weight loss diets violate the conservation of energy and matter. (The "I lived on just water for 10 years" diets do.)

Feces contains calories. Therefore conservation of energy isn't the only limiting factor - conversion and usage matter too.

There's no "conservation" argument that says that conversion effectiveness is a constant. Heck, there's no argument that says that calories/pound is a constant.

> But the direct cause of weight loss in IF is that you simply do not eat as much.

Nope. You lose weight when your body "releases" more mass than you're taking in.

> Because any other hypothesis has to explain why it violates the conservation of energy and matter.

This comment is so infuriating. I may not be a genius, but I did manage to eek out a degree in physics. I think I, and anyone here on HN should be given the benefit of the doubt that they can figurer out if energy conservation is being violated.

Simply from a principle of assuming that the person suggesting the hypothesis is not an _idiot_, you could infer that any of these alternative hypotheses do _not _ violate energy conservation.

I have found myself arguing with people who took the view that the conservation of energy and matter does not apply to sufficiently complex biological systems.

I am quite serious.

The relationship won't be linear, immediate, proportional or unary. But it will be causal.

So... you agree with the comment you're replying to, then?

No one disputes that a body cannot burn more energy than it has taken in. However, other factors can swamp a "mere" 25% percent reduction in caloric intake. IF has been the most effective weight loss strategy for me, but it doesn't work forever unless you keep reducing the amount you're eating. Eating only every other day worked great for two months or so, but eventually the loss tapered off (this was 2010), and something else must be done. The body doesn't need nearly as much energy as we typically give it, apparently, and varying the amount discarded can affect weight gain or loss greatly.

One thing you probably overlooked: fat cells add to BMR.

While I didn't overlook it entirely, it's true that it is quite difficult to know how to account for it without , since resting metabolism varies widely ( http://en.wikipedia.org/wiki/Basal_metabolic_rate#Causes_of_... suggests more than 25% variation after accounting for a number of potential factors). My own anecdotes suggest that once the (my) body adapts to higher caloric intake, it discards much more of it than when times are leaner.

25% is for extreme outliers.

http://examine.com/faq/does-metabolism-vary-between-two-peop...

BMR varies mostly on body size. Taller, heavier people have a higher BMR because there's more of them to keep alive.

> Cut calories enough, you will lose weight. Raise them enough, you will gain.

That's true in the useless tautological sense.

I've read a case study a few years ago about someone who has to eat something like 10,000 calories a day, because after some serious illness, their body only takes in 20% or so.

Paper is also carbohydrates - albeit not ones that our gut can process. Any statement about "caloric intake" is so hard to measure to make statements about "caloric balance" vague. They are useful as a "small signal"[1] approximation around common steady states (which are often 1000-3000/kcal a day, although that's not a good characterization).

However, when you go away to this state, this approximation breaks down and stops working. A model that would have predictive power in the "large signal" setting would have to take your entire biomass (10 times as many bacterial cells, although only 10% of body weight; 30% or so of solid excretions; facilitators of many processes), and nonlinear effects of insulin, ketosis, and others.

[1] http://en.wikipedia.org/wiki/Small-signal_model

It's not the study you describe, but there's already a lot of research to support the thesis that eating fewer calories (and fewer calories alone) than your body burns leads to weight loss and better health: http://www.forbes.com/2009/05/22/low-calorie-diet-lifestyle-...

Not exactly what you're asking for but there's a bunch of nice summaries with links to studies here: http://www.leangains.com/2011/06/is-late-night-eating-better...

Same here. I tried low-carb for a while and while it was effective for weight loss, I found it very difficult to stick to. I know for a fact, though, that my body responds poorly to too many carbohydrates, so regulating sugars is important if I want to lose any weight (and probably also to stop myself from winding up diabetic).

I switched to intermittent fasting and I am losing weight and have more energy while having no problems at all sticking to the routine.

I skip breakfast, have a low-carb/high protein snack around 2pm and a normal dinner sometime between 6-8pm. So it ends up being about a 16-18hr fast. On Friday and Saturday, I'll relax the rules and have a larger lunch or maybe a midnight snack, since I tend to stay up later those nights.

That "Fat and Simple" is a fantastic writeup of the Hacker's Diet.

Check out Martin Berkhan's http://leangains.com for more about making muscle gains while fasting. There's a subtle difference between using fasting as a tool for weight loss and one for body fat loss, but it's a difference nonetheless—it largely boils down to better management of your macro-nutrients (proteins, fats, carbohydrates) versus "eating like normal" after a fasting period.

The most basic explanation is that you can fast whichever periods you would like (most do 16 hour fasts + 8 hour "feeding windows"), but you must:

  A) Lift weights no more than 3 days a week
  B) Lift heavy weights to stimulate muscle growth
  C) Eat more carbs / less fats on workout days (more calories)
  D) Eat more fats / less carbs on "rest" days (less calories)

Compared to most lifestyles (this isn't a diet) this takes a lot of mental preparation and calculation, so it is more daunting initially and less mentally draining as you go on and see results (as compared to a fad diet which is simple to implement but impossible to maintain). It's not easy but, once a routine is established and the learning curve is overcome, many people make the decision to keep the 'LeanGains' lifestyle for the remainder of their lives.

I've been doing this for two months, works great for me. I'm down six pounds, and ~%40 stronger. And I was already fairly lean.

I've been doing LG for over a year now. I swear by it!

In addition to fasting on the month of Ramadan, Muslims are “recommended” (i.e. it's considered virtuous but not obligatory) to fast on Mondays and Thursdays of every week. That sounds eerily similar to the 5:2 diet in the article. http://en.wikipedia.org/wiki/Sawm#Days_for_voluntary_fasting

Muslims also know what's called prophet David's fasting, which is to fast every other day. However, considering that includes water, it's considerably difficult to maintain. I'm not sure I heard of anyone other than David himself do it for a long period of time! http://en.wikipedia.org/wiki/Islamic_view_of_David

A lot of the scientific interest in IF started with studying Muslims during Ramadan. I assume that is why it is similar.

Am I the only person who becomes extremely irritable once their blood sugar gets low? I can't imagine fasting for a day - I'd have no friends left by the end of it.

If you feel this way there's a good (IMHO) chance it will pass. The normal high-carb diet many of us eat results in spiky glucose levels. If you switch to a low carb diet you really feel it for a day or two. But then your glucose levels start to stabilize, and you don't feel the peaks and crashes anymore. You also don't tend to have sudden, intense hunger nearly as often, so it's easier to not eat between meals and to feel satisfied sooner when you do eat.

I've never tried fasting, but I've been on a paleo-esque diet for a couple of years now, and I rarely get hunger pangs or feel that "low blood sugar" feeling.

The fasting idea is interesting, I'll probably experiment with it.

Are you sure your blood sugar level really is low (hypoglycaemia), that is, have you had it measured? Idiopathic postprandial syndrome is apparently much more common, presents similar symptoms except blood glucose levels aren't actually especially low and unlike hypoglycaemia, it does not appear to be dangerous (unless you're driving and it interferes with your concentration).

If you suffer from actual hypoglycaemia, I would not recommend leaving it untreated.

In the case of idiopathic postprandial syndrome, episodes seem to be brought on by the steep decline back to normal blood sugar levels, as opposed to actual lack of glucose. What this means is you can avoid the problem by not consuming sugary food and drink in the first place, or combining them with other, non-sugary foods. Basically, don't let your glucose levels get so high in the first place. Fasting for a day shouldn't bring on an episode (although you'll certainly be very hungry!) - eating sugary foods, then fasting, will, however.

Of course, YMMV and I'm not a doctor or even a nutritionist.

Thanks for posting this! I've had this problem for a while and was convinced I was hypoglycemic but when I measured my blood sugar level, even at the peak of the symptoms, it was always perfectly normal. I had the blood glucose meter (and paranoia) because my sister is diabetic and I was afraid I might be too. It's somehow very comforting to be able to put a label on this and to know that it's not uncommon and (presumably) not dangerous.

I was always told that the thing that makes you irritable and cloudy-minded before eating breakfast in the morning is 'low blood sugar'. Sounds like it's probably just 'being hungry' :)

I was like that when I started IF. I'm much better now. The biggest thing was reminding myself that I was crabby because of the food and I'd be able to eat soon enough.. that normally put me on the right track.

It's hardly an issue now, which I love.

Your body adapts quite quickly. I don't eat until noon, and am full of energy in the mornings.

My brother tried, and it only took two days for his system to adjust.

I get the same way from time to time, especially after a workout. I feel (but could very well be wrong) that it's a sign of insulin resistance.

I've started to fast for a 24 hour period once a week (lunch on monday is my last meal until lunch on tuesday). I drink tea and water. I'll break my fast early if I have any signs of feeling unwell.

I haven't noticed any changes, but I was already in good shape, slept well, and what not.

I'm not sure I buy the health benefits for people who are already healthy. I tend to favor going by what the experts say, and overwhelmingly they say to eat normally every day. The more progressive might admit that there's value in further study.

On a different note... A couple years ago (long before I started fasting), I was in a meeting and I got super hungry. It was painful. I realized that many people live with this daily for decades. I think going hungry for a short period of time might make some people more empathetic.

> I tend to favor going by what the experts say, and overwhelmingly they say to eat normally every day. The more progressive might admit that there's value in further study.

I tend to follow experts when I don't have time to do my own research. But when I do, I find -- very often, with nutrition advice, and too often for comfort with medical advice -- that there's actually no scientific basis for these recommendations; rather that they are somewhere between "leap of faith" (that is sometimes provably wrong), superstition, and "that's the way we've been doing for a while so we assume it's the right way".

For example, many experts still insist that you should limit egg yolk consumption to no more than a few a week, although there's no science behind it - just a 60 year hypothesis that's been repeatedly disproved over the last 30 years (although the belief is so strong almost no one seems to be aware of those results).

And many still insist that the more cushioning for your ankle on your shoe the better - although there was never any research indicating that this should be true, and there is very consistent evidence showing that it is in fact harmful.

> On a different note... A couple years ago (long before I started fasting), I was in a meeting and I got super hungry. It was painful. I realized that many people live with this daily for decades. I think going hungry for a short period of time might make some people more empathetic.

I had fasted for 21 days once, and did not feel any discomfort throughout (on the contrary - up until day 14 or so, I felt disgusted at the thought of food; after that, it just wasn't appealing). And then I felt hunger. Which is something completely different from appetite, which is what I referred to as hunger before.

hunger is something that I've only ever felt at the end of the fast, and at the end of an army training camp that didn't provide enough food -- and I assume most people in the western world never do (although you might have - I can't really tell).

It's not pain. It's an obsession with food that will not go away when you do something interesting, which is unlike food craving or appetite - but I can't really put it into words.

Just a personal aside on the egg yolks - When I was 20lbs overweight, my cholesterol was a little above 200. I've since lost weight and eat 4 whole eggs for breakfast, and my cholesterol stays around 130, unfasted. I'm careful when it comes to simple carbs but don't avoid red meat as much as I should, given my genetics.

It took me long enough to get used to eating every 3 to 4 hours. Now this?

Come on nutritionists, where was this theory when I was in high school and would randomly go for two days without eating ...

PS: eating every 3 to 4 hours has brought the biggest gains to my leanness of everything I've tried. Even better than running every day.

There is no contradiction between eating every 3-4 hours and intermittent fasting. They occur on different time scales, you're going to be ok.

The big thing about intermittent fasting is that the rest of your diet has to be 'normal' as well. If you were like me in highschool, my 'intermittent' fasts were broken by... not optimal food choices.

I've also been doing this for awhile now. The program I'm on is called LeanGains http://www.leangains.com/ and I've been pretty successful with it. I've went from about 15% BF to 10% with minimal muscle loss.

ADF is the unknown secret to solving many modern ills ... or so I think. :)

I've had many conversations with three doctors about it and my thought is our bodies haven't caught up evolutionary wise to eating each and every day.

I have no proof outside of personal results, which I understand doesn't make it a reality. I could be a freak. lol

They key is not eating at all for a full 24 hours including your sleep cycle and then to only eat a normal meal on the days you eat.

I think this is actually very likely to be true. Think about living as a hunter-gatherer. Some days you just won't find/catch anything. Maybe you snack on a few insects. Other days you bag an antelope or find a big patch of berries and you have more than you can eat. Alternating between fast and feast every few days seems like it would be quite common. Eating a regular 3 meals a day is probably not the norm.

  So, two prehistoric men discuss cooking:
  - cooking meat should make you live longer
  - I don't know, man, my father always ate raw meat
    and he lived without any problems all the way
    till the old age of twenty one!

My point being, just because it's the old way, doesn't mean it's the better way.

The obvious counter to that argument is that people didn't die of obesity, we didn't have antibiotics yet. :)

> They key is not eating at all for a full 24 hours including your sleep cycle and then to only eat a normal meal on the days you eat.

I've gone on 7-21 day fasts, with good results and improved health. I agree with you, except I think the "24 hour" limit is rather arbitrary - up to 30 days yearly is common in some eastern religions with no irreversible damage (note - I'm not recommending everyone go on a 30 day fast; just that 24 hours is arbitrary, and the real limit is apparently some 30 times higher)

I'm fasting at the moment for Ramadan. It goes for 30 days and theres no eating or drinking from sunrise (5 ish) to sunset (6ish). Actually the fast includes a lot of other things besides food. If anyone has any direct questions I'd be happy to answer them.

The experience is not comparable:

GP and myself are talking about avoiding food (but not water) for periods of 24-720 hours.

Ramadan fast is avoiding both food and water for ~13 hours (for 30 consecutive days).

Not a judgement of anything - but that's not what we were talking about.

The article is not very clear behind the science of intermittent fasting - for those who are interested, do definitely read Alan Aragon's article [1] as well as /r/advancedfitness.

My personal view is that meal frequency is irrelevant for body biochemistry. What is happening is CNS (central nervous sytem) Adaptation - you are, for the first time, truly understanding how really hungry you are. Your body begins to understand that it does NOT need to eat breakfast, or eat something every 4 hours or eat a dozen nachos as an evening snack. When this happens, you automatically balance out on calories in vs calories out and you start losing weight.

I think this is a workaround for a bug in our brain - it makes pessimistic predictions for food availability and hunger responses.

[1] http://www.alanaragon.com/an-objective-look-at-intermittent-...

I would wager this depends a lot on the type of activity you're doing.

Sometimes after a really hard boxing practice I can be so hungry that I physically can't eat any more food, but I'm still hungry. And no, it isn't just a bug in the brain, the calorie tracker also agrees that I haven't eaten enough.

> Sometimes after a really hard boxing practice I can be so hungry that I physically can't eat any more food, but I'm still hungry.

For me it is the complete opposite - I can't eat or even think of food for a while, and am definitely not hungry or have any appetite -- and the harder the practice is, the longer it takes appetite to recover. (My practice of choice is thai boxing, btw...)

This is usually an hour after practice. Takes a while to get home, take a shower, prepare the food etc.

very true - but one is not asking you not to eat after a boxing session. One is asking you not to eat anything for the other 16 hours (assuming eating and boxing fall in the 8 hour block) - which is when your body, conditioned by Kellogs, starts sending panic signals.

This advice is sort of along the same lines as the Warrior Diet which preaches fasting all day and preserving yourself for one large prepared meal to quench your warrior instinct. I follow the Warrior Diet 3-5 days/week. It recommends eating vegetables during the fast (some lean proteins if you workout a lot) and also ways to start your one big meal. The diet plan instructs you to eat some vegetables first followed by protein and then grain.

I really like this diet, but it is difficult to follow everyday. I would say I have 2 cheat days/week where I eat a lot of junk food. This summer ice cream has been my haven. All in all I am down 40lbs since the beginning of this year... Should mention and thank the slow carb diet for at least 30 of those lbs... (note:slow carb diet is eating every 4 hours....)

I see people here mostly talk about effects fasting has on health but not much about effects on mental/physical performance. If you live longer but you're less effective in what you do, fasting turns into a much less attractive choice, at least for some people.

From my very non-scientific experiments, I can tell that my bullet (1 min) chess rating suffers a lot when I'm restricting my calories. It's really hard to measure how fasting would affect a more complex activity, like programming...probably the impact is smaller but there certainly is an impact. With restricted calories, I usually need to add caffeine to the mix to suppress my hunger and make it easier to concentrate.

I tend to be a lot more productive when fasting.

I also tend to be more impulsive, so staying focused on the thing I should be doing, as opposed to what I want to do, is definitely an issue.

That being said, the time I save by not eating breakfast is also nice :)

Here you can rate if those "fasting" methods/lifehacks works or not: https://didthis-actionwiki.appspot.com/tag/fasting

To create new ones: https://didthis-actionwiki.appspot.com/create, or fork those already in eg. https://didthis-actionwiki.appspot.com/intermittent%20fastin... (just add "/copy" at the end of the action link).

I've practiced inttermittent fasting for a bit (eating absolutely nothing with calories one day a week), and, apart from losing weight (which I can't attribute entirely to IF, since I was also eating less in general, but IF definitely helped), it was just more convenient for me.

I prefer to just eat nothing one day, which is relatively easy since I work/do stuff during the day and have to take time out of the day to eat, and then indulge the rest of the week. IF enabled me both to not keep in mind how much I eat six days out of the week, and to just simply not eat anything for one day. I consider it a great success.

I've got a friend who has been on something akin to the warrior diet without knowing it. He works as a server, so He's up all night and sleeps during the day with one grand, large meal he eats in the afternoon. He did it more as a convenience than anything, but has lost about 20lbs in the past few months. I normally eat every few hours, but may try this out as long as it doesn't adversely impact my work or exercise regime.

I saw that other article about fasting and decided to give it a try yesterday. I made it about six hours before I realized my concentration was way off and my emotional balance was out of whack.

Granted I was also working a freelance job. Which in retrospective was probably a bad idea. However I did learn something about myself. And next time I try fasting I'll make sure that I don't have anything pressing due the same day.

A big thing to stress here is that you eat normally the other days. I know some people who have tried IF who gorge on food once the fast ends, and end up no better off than not fasting at all - calorie wise at least.

That's good advice if you want to lose weight, but a number of IF studies were calorie neutral (double rations on non-fast days) and that's why I find it interesting: it's triggering some of the same benefits as CR but without restricting calories, which means it may be a much easier lifestyle to maintain.

Right now is the month of Ramadan.

Fast too much and your body goes into famine mode, where your fat storage management system is convinced that this month's food catch is low, and it is likely this will be a lean year. Therefore store everything you can to fat and keep energy outputs low. Causing obesity.

When I was 26 ish, i fasted for 3 days. I'm 30 now. Dumbest thing i ever did. I gained weight from that DAY I started eating again forward, and it's been a battle of the buldge ever since.

The "starvation mode" idea comes from the Minnesota Starvation Experiment.

Wherein the subjects were starved. And are you ready for the punchline?

For months.

There is such a thing as a starvation response. A slight drop in basal metabolic rate, an increase in cortisol and a bunch of other changes. Psychologically, subjects were obsessed with food.

But it takes time to kick in. Weeks. Months even.

One or two days is not going to do it.

Maybe, just maybe, one day when you were 26 you entered your late 20s and received the corresponding metabolic slowdown.

There have been many, many papers that show that starvation mode does not kick in until after about 36-48 hours of fasting. Intermittent fasting is usually a 16-24 hour fast.

For those interesting in the papers [Leangains][0] has a long informative narrative connecting the papers together.

[0]: http://www.leangains.com/2010/10/top-ten-fasting-myths-debun...

Do you attribute your three day fast as the only, or main, factor to your 'battle of the bulge'?

Yes, this is not a particularly scientific study here.

Source?

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