Hacker News new | past | comments | ask | show | jobs | submit login
Empty-Stomach Intelligence (nytimes.com)
94 points by lbr on Nov 11, 2013 | hide | past | favorite | 70 comments

This reminds me of a passage from Ben Franklin's "Autobiography" about vegetarianism, but could be reinterpreted as a statement on the benefits of being hungry:

"When about 16 years of age I happened to meet with a book, written by one Tryon, recommending a vegetable diet. I determined to go into it. My brother, being yet unmarried, did not keep house, but boarded himself and his apprentices in another family. My refusing to eat flesh occasioned an inconveniency, and I was frequently chid for my singularity. I made myself acquainted with Tryon's manner of preparing some of his dishes, such as boiling potatoes or rice, making hasty pudding, and a few others, and then proposed to my brother, that if he would give me, weekly, half the money he paid for my board, I would board myself. He instantly agreed to it, and I presently found that I could save half what he paid me. This was an additional fund for buying books. But I had another advantage in it. My brother and the rest going from the printing-house to their meals, I remained there alone, and, despatching presently my light repast, which often was no more than a bisket or a slice of bread, a handful of raisins or a tart from the pastry-cook's, and a glass of water, had the rest of the time till their return for study, in which I made the greater progress, from that greater clearness of head and quicker apprehension which usually attend temperance in eating and drinking."

Perhaps Steve Jobs's "stay hungry, stay foolish" quote was literal as well.

> The finding was startling, but “it makes sense,” Horvath says. “When you are hungry, you need to focus your entire system on finding food in the environment.”

I never liked these types of rationalization. If the result was opposite, you can easily say that it would make sense because when full, you can concentrate fully on the task at hand, rather than on finding food.

I agree. This logic isn't perfect, but at the same time... I think there is no greater drive than that for sex, food, self preservation etc. I have to imagine that this drive forces you to focus and work.

When you are full... sure you can devote your attention to something else. But the body also has a "rest and digest" mode.

Blood flows to the core to allow digestion. Pupils constrict. The body sends less blood to the lungs, and decreases O2 exchange. Hear rate slows.

These are all responses that make people want to curl up and sleep. Not create, work or work together.

No you can't. This is one of the first fallacies taught in Logic 101. If A then B, does not mean if !A then !B.

His or her point is that the "evidence" at hand can be rationalized either way. That is because there is no causal evidence about the relationship between hunger and productivity adduced here.

Thanks for clarifying the point for me instead of simply downvoting. I see what was meant here now. But I think the point could have been made better by pointing out the lack of causal evidence, rather than complaining how it could be rationalized because pretty much anything in the world can be rationalized if you try hard enough.

The point was made best because it presented a counterexample. Merely pointing out 'ad-hoc fallacy' (or similarly, my pet hate 'citation needed') might make the author and a few other people feel good about themselves for seeing the flaws, but it's a lazy response which adds the smallest value greater than saying "I disagree", and is better suited to a points-scoring exercise rather than a discussion.

Even assuming that the human brain somehow "works better" in a state of hunger (which this study does not prove), I would still do better work in a state of satiation.

The number one factor for doing good work is to sit down, get in the zone, and stay concentrated on your work. I find that being hungry is very distracting --hunger constantly nagging you out of your task with the urge of getting up and grabbing a snack. So independently of how well hunger makes the brain work, for me hunger is detrimental to the only thing that matters.

You say you "would still do better". Does this mean you've not actually tested your belief empirically?

I find hunger is one of the least well understood of our bodily functions, despite it being accessible to every one of us. Few people test it.

From my experience, and from the experience of everyone I've every talked to who tries intermittent fasting: You won't get hungry, once you adapt. Most of us adapted in a few days.

I don't eat until 12-1, and I get up around 8. Hunger never bothers me until lunchtime, and I feel clear headed and productive all morning.

If you HAVE tried this experiment, then apologies. But I find it very irritating that so many people i. Have very strong opinions on the matter of fasting ii. Have never experimented to see how they react to fasting

I've always had a tendency to forget to eat. Recently, I've been forcing myself to eat something in the morning (I look for something with fat or protein, preferentially) and I've noticed that those periods where I have no energy, can barely move, can't think and get stuck in horrible, repetitive ruts, etc. get much better.

Ditto. My hunger mechanism doesn't seem to work quite right- sometimes I'll feel ravenously hungry and then find out that a single Oreo is sufficient for satiation, other times (much more often) I don't realize that I should be hungry until I start eating (if even then). I once literally forgot to eat for almost three straight days, and could not figure out why I was so tired and having so much trouble getting homework done until someone asked when I had last eaten- a large pot of oatmeal solved the problem.

Being reminded and required to eat at least two legit meals a day is one of the great benefits of having since acquired a wife.

Thanks for reminding me to get some food. I have the same experiences, as long as I don't move too much. (Sports and moving around town will get me hungry.)

Fasting signals your body to aggressively conserve resources, making less available to you and optimizing for maximum fat content. Which is why it's not an effective dieting technique. When you "get used to it" your body has reduced its energy consumption but also the energy available to you and your brain.

The mice are doing better at getting themselves fed but I wonder what the impact of hunger is on higher order functions like programming, relationships, management, etc...

It takes a very long time for your body to go into "starvation mode." Intermittent fasting is actually a reasonably effective dieting technique assuming you don't binge eat afterward to "make up the difference."

Good source: http://www.leangains.com/2010/10/top-ten-fasting-myths-debun...

> Looking at the numerous studies I've read, the earliest evidence for lowered metabolic rate in response to fasting occurred after 60 hours[0] (-8% in resting metabolic rate). Other studies show metabolic rate is not impacted until 72-96 hours have passed (George Cahill has contributed a lot on this topic).

> Seemingly paradoxical, metabolic rate is actually increased in short-term fasting. For some concrete numbers, studies have shown an increase of 3.6% - 10% after 36-48 hours[1,2].

[0]: http://www.ncbi.nlm.nih.gov/pubmed/3661473

[1]: http://www.ncbi.nlm.nih.gov/pubmed/2405717

[2]: http://www.ncbi.nlm.nih.gov/pubmed/10837292

Parent seems to be talking about long-term permanent strategy, not sub-72-hour increments. I apologize if that was incorrect.

I said I don't eat until 12. A 16 hour fast, typically.

Do you have any support for your speculation?

I can spin an equally convincing story, that fasting tells your body to mobilize resources, in order to better catch an animal.

And the whole energy-conserving thing is easily testable in a lab, just by looking at metabolic rates. (With a bit more ingenuity you can probably find out how to test it at home, too.)

See Nav_Panel's comment. Metabolic rate lowers after 60-72 hours.

He specifically mentioned intermittent fasting, which is generally 16 hour fasted, 8 hour eating window, repeat.

One-day-on, one-day-off is another common protocol.

I wonder the same thing. For me, I become far more productive and focused when I'm slightly hungry. Great for late night work by myself, reading, emailing.

But being hungry also makes me a bit less social... I try not to be hungry when I'm working with people.

What I wonder is if I'm more creative when I'm slightly hungry. And I think I am. Hard to quantify.

I think it's all about being able to focus the hunger into whatever you need to do - I just can't do it when I know the food is right there - my brain simply knows I'm not working towards getting food and it's very distracting.

It's different than when I'm in the field - I know I'll eat when I finish the job, so I just focus all I've got into doing the work faster.

> I find that being hungry is very distracting --hunger constantly nagging you out of your task with the urge of getting up and grabbing a snack

That only applies if you are actually experiencing hunger. I've been doing intermittent fasting for a couple of years and I haven't been hungry one single day - I don't even remember what it feels like. I eat once a day, usually at the end of the day.

It's well known that natural level of catecholamines (adrenaline, noradrenaline) are raised during the fast. As a result, most intermittent fasters report increased focus and alertness during this period. This article about ghrelin is yet another piece of the puzzle of why IF works so well for some people.

Cortisol is elevated during fasts and thyroid hormone lowered. Endotoxin absorption is increased by large meals. I would guess daily fasting might be a bad idea. It's perhaps like veganism, where after a period of years it could catch up to you in a bad way.

Of course it makes sense that people would be a bit sharper with elevated adrenaline and cortisol. But those fundamentally put stress on the body.

What duration of fasts are you referring to? I had seen research on Ramadan fasts that indicated that short term fasting did not increase the total amount of cortisol, though the timing shifted.

I was under the impression that short term fasting was metabolically different from term fasting.

My source had been Martin Berkhan's blog. He cites the Ramadan literature in point 8. I'm not well placed to evaluate the papers as I lack expertise.


Ramadan fasting would be a brief period of ~12 hour fasts during the day, right? No biggie. The guy above was saying he eats one big meal every day, indefinitely. I'm no expert but that sounds like a bad idea.

The rule of thumb with stress is that low but chronic is way worse than acute. With that in mind maybe don't eat at all one day a week, but get your three squares the other six.

Why three meals per day? If you're not an expert, then can you point to experts saying that eating just once or twice per day is "chronic stress" and a "bad idea"?

Why one? Normal humans for approximately forever choose two or three spaced meals. The onus would be on those advocating otherwise. Let me know when you find the study where people ate only one meal a day for a year.

> The onus would be on those advocating otherwise.

The onus would be on those making claims. It's for him to support the claim that one a day is healthy, but you are conversely making unsubstantiated claims about the health effects of just eating one meal a day, and the onus is on you to substantiate those.

It is one thing to ask him for evidence of his assertion, another to make your own and expect him to disprove them.

Here's a Ramadan fasting timetable for the UK this year:


So more like 18 hours.

I don't know if I'm different, or what -- but I simply cannot concentrate on an empty stomach. When I find myself just staring at the computer screen, unable to write code -- it's usually because it's 11am and I didn't eat enough breakfast, or 11pm and I didn't eat enough dinner. It's not the distraction of hunger, it's just that my brain isn't getting the energy it needs to think properly. I have to go snack on something (usually substantial) to get enough energy going back to my brain -- and then I'm fine.

In fact, I've often been mystified by people trying to lose weight who barely eat anything all day, yet still manage to get work done effectively, participate in meetings intelligently, etc. I wish I could, but I swear, when I'm hungry it's like my IQ is cut in half.

Still, just from talking with friends about it, it seems like I'm the outlier here.

I think people do react differently to hunger (as well as lack of sleep, alcohol, caffeine etc) -- however I recall hearing that hunger does indeed make us restless -- the theoretical rationalization was it stimulates searching for food, as opposed to sitting down and searching for the meaning of life.

That lines up pretty well with my personal experiences -- and it might explain "smarter" mice -- mice that actively seek out some kind of solution -- without generalizing to humans preforming theoretical tasks well on an empty stomach. On the contrary, my impression was that there are numerous studies that show that free (healthy) meals at schools boost academic performance.

This is somewhat related and quite interesting.


I have a similar issue. From what I can tell using my layman's understanding of the nutrition involved, fat or protein will give you steady energy throughout the day, but sugar or refined carbs (like white bread) will just temporarily spike your blood sugar and lead to much unhappiness a little later.

Either way, if I don't pay attention to my energy intake, I don't necessarily get hungry - I just end up slouched in front of the computer accomplishing nothing without the energy to even get up and move. My thinking falls into repetitive ruts - I'll attack a problem from the same direction over and over, neglect any sort of creative solution, or even fail to execute a basic troubleshooting routine I should know applies.

The article still seems to apply, though: being too full is really terrible for maximum motivation and really getting things done. It may be best to eat good, solid meals, but none of them too massive, and not just before you need to do hard work.

I'm the same way. I've never understood people who work all day and, at 11pm, casually mention that they haven't eaten since last night. If I even skip breakfast I can't get any work done until lunch.

I agree - hunger for me is a distraction, and the sooner I can take care of it, the sooner I can get focused again. Eating could certainly be a distraction if you overeat to the point of being tired after a meal, but eating properly, imo, takes care of something that would otherwise be hindering my productivity.

I wonder why it's so difficult for news reporter and journalists to link to the actual paper. "According to researchers at Yale Medical School ..." great start (irony ;) ). Here's the paper link (unfortunately behind a paywall): http://www.nature.com/neuro/journal/v15/n8/full/nn.3147.html

Given the paper I find these sentences highly speculative: "... causes mice to take in information more quickly, and to retain it better — basically, it makes them smarter. And that’s very likely to be true for humans as well."

To broad and too vague, ... there are too many influences on knowledge acquisition (information intake)

Always check Google Scholar, which in this case ( http://scholar.google.com/scholar?cluster=866211161589883826... ) turns up two public copies: https://www.med.upenn.edu/ngg/user_docs/Dietrichetal2012Natu... / http://www.researchgate.net/publication/228063201_AgRP_neuro...

Not that I'd place any weight on this. Mice responses differ from group to group, breed to breed, and need not generalize to humans at all ( http://www.gwern.net/DNB%20FAQ#fn97 ). In particular, if hunger really did improve general cognitive performance in humans, it should be trivial to show this! Take two groups of undergrads, keep them busy for a few hours so they miss lunch, administer IQ test; done.

In fact, it's so trivial that it's been studied in any number of contexts, particularly dieting: http://scholar.google.com/scholar?q=hunger%20cognitive%20per... I dunno about you guys, but skimming over the abstracts and titles, I'm not thinking 'hunger will turn me into a genius'...

This, in light of Norbert Wiener's requirement that good democracy has access to adequate information for making decisions, is a perpetual source of fury for me.

Even when papers are, like this one, paywalled, the abstracts are still useful. Also, the author's names and even the original title of the paper are very useful and so are its references.

Tip: in many fields, the authors publish the same paper free on their own websites.

Hunger and appetite are not the same thing, although they are often conflated. I doubt anyone posting here has actually felt hunger.

That feeling of "I should eat something now" is either appetite, or ritual (and/or carb addiction). If you are not malnourished, it often takes 20 days of fasting for hunger to appear (as many as 40), and when it arrives, you'll realize it is there: It's not a feeling that goes away if you're immersed in a book, work project or video game. It's a feeling that you'll be willing to fight for food now, if needs be. (Addiction can also cause that feeling, but addiction will go away if your mind is taken with other things. They just feel different in a way that I don't know how to describe).

Despite living in a western society, I have experienced it several times. The first, involuntarily (was a vegetarian in the army, and despite rules to the contrary, there was only sufficient amounts of food if you ate meat), and not fasting - I just wasn't eating enough for over a month, and then it came with a sudden force.

The other times, I lost my appetite, so I didn't eat until it came back (as I often do). Usually, appetite comes back within a day or two. A few times, it took over 10 and over 20 days.

Food consumption, hunger and appetite have no simple linear relationship. After two days of fasting (voluntary or forced), the appetite disappears. I know that seems very unlikely to anyone who hasn't tried it, because it seems like the appetite (or a feeling you call hunger) just keeps getting stronger when you don't eat - to the point that it would be impossible to sustain if it continued linearly. But it doesn't - it just goes away after a couple of days, your body switches to some kind of maintenance mode (characterized by ketosis) that actually feels good.

How do we reconcile this with hunger causing ego depletion and choice fatigue? (http://www.nytimes.com/2011/08/21/magazine/do-you-suffer-fro...)

Reconciliation: NYT wants to report on something that sounds interesting and people will talk about.

Choice fatigue / ego depletion in part prevents you from consciously overriding your lower level drives. It does not turn you into a mindless zombie. It just prevents you from, say, maintaining your diet by holding firm when part of your brain is screaming "you deserve ice cream!". You may find yourself becoming extremely efficient at convincing yourself you need food, and particularly a big pizza and a litre of ice cream, and great at self-rationalising why you deserve it despite being on a diet.

So there's any number of things that might be happening: The mice might have been trained with food. If they expect a reward for completing the intelligence tests, then it makes sense that they'd focus intensely on carrying the tests out successfully just to follow through their drives.

Alternatively, it might be a general increase in focus coupled with the absence of any way for them to satisfy their drives gets "redirected" into focusing on the task at hand. When I'm hungry or really badly want something I can't have then and there, I'll often find I can be super-efficient, though feeling restless. Of course the problem is if there's any way I can turn to satisfying my desire for ice cream instead at that point, I'll grab it.

Third, it is not a given from the description that the mice will be feeling hunger. When doing intermittent fasting (18 hour fasted, 8 hour eating window), I feel hunger only for the first day or two. Past that, I start feeling apathetic to food, and need to focus on eating enough in my eating window. Yet I still feel much better outside my eating window. My self-control in terms of food in particular is rock bottom the first day or two, but if I make it past that, I'm good. (When I go off IF in periods, it is actually usually because it gets incredibly tough for me to eat enough while meeting my protein goals for my power lifting, for extended periods of time)

Or, of course, the study might just be severely flawed.

Though for my part when I pull all-nighters I tend to try to avoid eating - I'll drink very low calorie drinks (very diluted juice, at around 10kcal per 750ml glass for example) slowly, and that seems to work better for me in terms of maintaining focus than downing lots of calories. Coupled with my experience with intermittent fasting, I'd much rather be in a semi-fasted or slightly hungry state when trying to focus on something important, than full. (Though at the end of an all nighter, the fatigue often means I find myself "out of control" eating wise the following day, at which point I often make a decision to "surrender" and just subtly try to "give in" to the least damaging urges rather than sticking firmly to diet, in order to retain as much as possible of my by then very limited willpower for more important stuff until I've rested; to me that also feels like it works better - then again it could also just be that believe is just my brain chemistry convincing me to continue feeding it sugar.... ;) )

There's similar findings that a hungry stomach can make you more awake and even cure jet lag. It goes back to the 80's - Ronald Reagan used the technique to look fresh when landing across the globe.


When I learned about it last year, I figured it might also work as a technique to pull off all-nighters and tried it out whenever we had a press embargo for some feature we hadn't even created yet. It seemed to help a lot, especially for someone like me that usually needs an absurd amount of sleep to function.

There is a difference between being actually hungry, and beginning to feel the need to eat. Other commenters are comparing hungry kids not being able to focus on learning, which is absolutely true. Its not just the hunger for them, its about food insecurity. They don't know if they'll get food tomorrow, so the idea of staying fed is primordial there.

That said, for me, a state of feeling light-headed with the need to eat in the background works best. Satiation is a never ending pit, you'll need to fill in 15 minutes after you last felt satiated. But if you can ignore that little sugar-triggered signal, focus becomes both easier and intense.

Since I started working from home, I found that I'm super focus and productive in the morning after consuming a cup of coffee. My productivity is at its lowest after lunch, even a light one, feeling my glucose is running low.

I found it helps to take a small break and do 15 min walk and come back to work re-boost my attention again. Another thing that helps is to maintain a low in-door temperature definitely adds more O2 to my brain. Maybe that's why my last workplace is always so cold with AC blasts at its max.

Have you tried a standing desk or a walk and nap after lunch?

Those things did make a difference for me.

I'm having trouble calibrating what people mean by "hungry" in this thread.

Obviously they're nowhere near the eating disordered end of "hungry". (Where people use a lot of cognition on counting calories and working out how to burn more calories or evade monitoring, to the point that physical movements slow down, because they're concentrating so hard on other stuff.)

But is this just missing one meal? or missing a day of food?

This is actually one of the reasons I do what is now called "Intermittent Fasting". I found in my teens that I was much, much more focused and alert on an empty stomach. I've always assumed it had to do my insulin response to meals as low-carb diets had a similar effect but not eating during the day was just easier.

For me, almost everything feels better with an empty stomach. Studying, working or just having a good time. I do some small water fasts during my month (1-2 days fasts) and these days are definitely the best ones: I feel lighter with a clearer mind.

But there is on thing in the article that I think is BS: “When you are hungry, you need to focus your entire system on finding food in the environment”. I'm not an expert in this area but I always believed that this benefits were due the shutdown and cleanse of your digestive system.

I see a major flaw in the generalization from hungry mice solve a maze faster to hungry mice are more intelligent (let alone humans). Supposedly you train the mice to solve a maze by giving them a food reward. It stands to reason that the hungry mice are simply more motivated to get the food reward. If you had given the mice some other kind of reward when they solved the maze (e.g. sex) then the hungry mice may not solve it faster, but sex deprived mice may.

That's exactly what I've been noticing with myself. As time passes from my last meal, I start becoming more productive, I can read faster, remember many more things... I feel like my brain weights less. On the other side, just after having had lunch I need to have a short nap, otherwise it takes me like 1h to be fully operative again.

I also find that I perform best when I fast for the morning, and then have a rather large lunch. Its a little hard around 11am, but I don't crash as easily - and I'm able to push through problems easier afterwards.

The only thing I find is that it sometimes impacts on my creativity; I'm not able to think of alternate solutions.

The stimulation of hunger, the researchers announced in the March issue of Nature Neuroscience, causes mice to take in information more quickly, and to retain it better — basically, it makes them smarter. And that’s very likely to be true for humans as well.

I am a little sceptical of the claim in the last sentence.

When the lab rats are in the maze, is the prize for successfully exiting the maze a piece of cheese or other food? If so I wonder if this test effective. If I'm hungry I can probably find the fastest route to a store or restaurant, but I'm not sure about improved calculus skills.

I notice this all the time - focus better hungry. Just did some research and dug up the article.

Same here, I feel more focused and have stronger mental acuity when my stomach is empty

my experience is the same. I usually skip meals in the lab for this reason.

Hunger works for me. I'm less likely to procrastinate if I'm hungry. I can concentrate better. I can more easily tune out everything else.

Music : Ears :: Hunger : Brain, at least when concentrating.

So should we be giving kids state sponsored school breakfasts or not?

Good question. I once saw a documentary about this topic. They pointed out a lot of the kids went to school without breakfast at home, because their parents were poor. After implementing a sponsored breakfast at school grades improved a lot. Unfortunately I don't remember the name of the documentary.

The poverty issue might very well mean that these meals might be beneficial primarily by counteracting chronic under/malnourishment and that this is a more important effect than any benefits of short-term fasting / hunger.

But there are other potential effects as well: It is one thing to be hungry if you are able to decide yourself what to do. Another when dealing with authority. We can tell when my four year old son is getting hungry before he notices it himself because he starts getting cranky when we try to interfere with what he is doing.

Purely guessing based on that anecdote, it might also well be these kids would perform better at what they want to do when hungry, but that they are more docile and find it easier to sit still and pay attention to the teacher when well fed.

For my part, I used to prefer to go to school without breakfast for many years, but then again I was usually allowed to sit and work on whatever I wanted most of the time in many classes, as I was usually ahead.

Of course this is all speculation.

Your speculation definitely resonates with me. I always had a hard time sitting still and paying attention in class if I was hungry. For whatever reason, if I've gone a little bit too long without eating enough, I end up experiencing sharp pains in my stomach that are incredibly distracting, even though I doubt I ever went long enough without food to truly have an empty stomach.

Yes this seems to be quite a commonly reported "fact" there are even charities here in the UK that provide school breakfasts.

This study basically says that Ghrelin makes you smarter. It may well be that this is to counter the effect of lower blood sugar due to hunger.

Being hungry could still make you "dumber".

So much for the "kids can't learn if they're hungry" argument for subsidized or free school breakfast and lunch programs...

I've heard the same thing somewhere, where if you need to go to the toilet that's the best time to make a decision.

I find that in this situation, my response is always the same: "Just do it.. be right back"


tl;dr: hunger makes mice smarter, likely to be true for humans as well.

The stimulation of hunger... causes mice to take in information more quickly, and to retain it better — basically, it makes them smarter. And that’s very likely to be true for humans as well.

So based on a so-called scientific study of mice, we have this great insight on how humans think. This study and ergo this article are either wrong, or mice are so close to humans in the way they behave that it's ethically and scientifically indefensible to conduct harmful and lethal experiments on them.

In other words, if mice are such a reliable proxy for human beings, we shouldn't experiment on them because they are people too. If they are not reliable proxies, then we need to stop using them as such.

That fundamental question is largely being ignored in the scientific community, but until it's answered, these studies are bad science.

Guidelines | FAQ | Lists | API | Security | Legal | Apply to YC | Contact