A Meta-Analysis of Blood Glucose Effects on Human Decision Making (2015) [pdf] | Hacker News Reader

A Meta-Analysis of Blood Glucose Effects on Human Decision Making (2015) [pdf]

gwern.net

92 pointsgwern18 comments

Fascinating. It shows the importance of having a consistent blood sugar level, especially when we are around expensive food choices. At the same time, it seems that we could use fasting (resulting in a low blood glucose level) as a motivation to work hard if we know that work will get us more food.

The results also showed that people had less patience, even when working for food.

Except work doesn't get us more food. I have a dollar on me, I know I can get a lot of sugar right now with that.

I've always wondered how productive I could be if I handed my access to spending money, plus a list of food I like, over to a trustee, and then told them to buy me food but only give it to me right as I finish things I care about. It seems like it would create some pretty strong conditioning effects.

You sure have to hate yourself to do that. Reminds me of some cruel scifi novels.

Until you slip up - because e.g. you gave yourself too big a quantum of work to do before your next reward, or something unexpected popped up that you need to deal with ASAP. Then you'll find yourself tired, hungry, frustrated and in a downward spiral - because you'll be quite likely making mistakes sabotaging your work instead of making progress, thus putting off your eating time further in the future.

And I'm not talking out of my ass; I screwed myself a few times like that with the whole "precommitment" idea, including losing quite a bit of money - instead of helping me focus, this only stressed me out further as I was desperately thin on funds.

Not saying precommitments are a bad idea, just make sure you can handle failures mentally before going full-Klingon on them.

Note the "food I like" part. I imagine that I could have a pantry full of Mealsquares or something similar (a nutritionally-complete but not-"tasty"-as-such food), and pots of black coffee, to keep me going monotonously until I managed to finish my work. The reward is the rich, fatty, sugary, salty, umami-y food; not food at all.

Haven't read the article yet, saved it. However, my experience is that I am usually agressive and stupid when hungry.

Looking forward to reading the whole paper.

As a type 1 diabetic, I agree with these conclusions, and I'd sum it up this way: when I have a low blood sugar, I feel anxious and want nothing more than more sugar inside me. Bouts of hypoglycemia definitely make me more impulsive. With a low enough blood sugar, time feels as if it slows down: I imagine this is linked to adrenaline... I can tell I have a high blood sugar (over 150) before checking when I feel grumpy (and bossy), I'm thirsty, and tend to have 0 appetite whatsoever.

Interestingly -- things that require long periods of concentration tend to lower my blood glucose (according to my continual glucose monitor) and stress tends to raise it.

If anyone would like to ask me any questions, I'd be glad to answer. :)

The paper makes no mention of subjects in ketosis. Would have been interesting.

Agreed. The brains of keto-adapted individuals can use ketones as a source of energy which are much more stable, although for a long time it was believed that brain relied on glucose.

Different parts of the brain run on ketones and glucose. It varies. I wish I had a source, remember it from neuro long ago.

My layman understanding is that glucose is the first choice. But stay off it for a day or two and the body starts turing fat into ketones as an alternative.

Yes that accords with my layman understanding as well. The body will go down the "path of least resistance" for energy and glucose is easier to metabolize than ketones. Deprived of glucones, the body will switch over and hum along once adapted.

If you're interested in the methods and related questions, check out this (4 part) youtube talk: https://www.youtube.com/watch?v=xG79jpAYxmQ&index=7&list=PL5...

So is this a contradiction of this? https://news.ycombinator.com/item?id=8695417

Judging from the abstract the tl;dr version is: "If you're hungry, you think about food".

Certainly aligns with my experience.

That's not what the article is about. It's about several competing theories for how blood glucose affects decision making, their predictions, etc. It's not about hunger per se (blood glucose and satiety are biologically different enough you wouldn't want to confuse the two).

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