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Comment by fchollet | Hacker News Reader

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.

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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

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...

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.

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.

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.

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.)

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.

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

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:

http://www.bbc.co.uk/asiannetwork/shows/ramadan/timetable/

So more like 18 hours.

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