The body is excellent at maintaining glucose concentration in the blood with food or with days of fasting. Glucose is the primary short-term energy source for most cells. The brain's energy requirements vary very little with "thinking" despite the assertions to the contrary in the introduction of this article. PET works by noting the slight transient increases in some brain regions with active thought, but moments later (as that 20% of blood flow goes swishing through the brain) more glucose is available. Meanwhile you are digesting sugars and carbohydrates, and your liver is supplying most of your fresh glucose if you are a fasting adult.
Already, before reading the article, I have a low pre-test probability of their hypothesis being true, so they need extraordinarily strong evidence to make their point. Instead, there is a very weak chain of experiments, poorly reported, with borderline statistical significance. Poor charts, no tabulated results, just terrible.
The primary problem is that they assert that glucose fluctuations occur due to the exercise of willpower. They try and fail to show this with their first experiment. However, their "results and discussion" combined section shows that their control group before and after glucose were very close to their post-intervention group glucose. p327 para 1.
This shows how weak their statistics and data are, and from this point, you can throw the whole study in the trash.
Suppose I made the argument "car crashes rely upon momentum":
- car crashes is a terse signifier; a high-level recognition of something that no doubt relies upon low-level phenomena
- momentum is a physical, and therefore, low-level, phenomenon
No one would say I said anything useful. They would say "well duh but why were they driving towards where they drove? were they reading a text? were they drunk? were they even to blame when they crashed? was the car fully-functional? what were the weather conditions like? how much experience driving had they had? how old were they? how good was their vision?" etc..
More or less this is what is going on with, at least, the headline implies:
- self control: high level subjective phenomenon (who is to say that every person has self-control via non-dissimilar mechanisms??)
relies upon
- glucose: a correlate. Correlates are mostly useless and used to fool people, even if r > 0, and even if r=~1. Correlation more often indicates that there is a combination of excitement and merely-coincidental yet spurious non-causality in >99.99% of measurements.
I don't blame people for wanting there to be a simple, chemiological explanation for things that are very important to their existence. But I do blame the people who are responsible for preemptively jumping the gun and broadcasting the suggestion that these questions have been answered, especially because they are reporting that it was solved via something as vulgarly facile as in vivo molar concentration of near-universal molecule
Even if it is unlikely that the claim is true in a fundamental and meaningful and not-merely-correlative sense, after so many decades of prior investigators having approached this obvious hypothesis..
Usually when such claims are broadcast, it happens in two steps:
1) Some researcher (often a PhD student) finds some correlation (with our without conscious P-hacking) that has p<0.0.5. Their thesis may depend on it. 2) Some news broadcaster makes a story from the article. Their job/income may depend on it.
Now who, exactly, would you blame.
control group glucose before: 102+/-21, after 103+/-18 intervention glucose before: 107+/-21, after 101+/-18 (+/-SD)
Wide confidence intervals, and critically important to note, the pre-test intervention baseline of 107 is much higher than all the other numbers. They do not show that this is not by chance, i.e. null hypothesis of no difference is not rejected. They don't state a P-value (even though this is now out of vogue, the paper is ten years old), likely because it is greater than the mythical 0.05.
These numbers are laughable, so much so that I do not even think they are fabricated. They also quote two decimal places even though their SD is ~20! Every detail of this paper is amateurish.
I also have a problem with the ethics of this study. They recruited students and paid them in course credits. This strikes me as being coersive.
I'm sure I could find more gaping holes in their reasoning, statistics, but I hope I've already shot it down. I'm not a neuroscientist by any means, but I do digest a lot of scientific papers. My guess for a real cause of this effect would be neurotransmitter depletion in key neurons involved in self-discipline.
In addition, the commonly stated myth that people "feel hypoglycemic" could be easily disproved in 99% of people if it was worth the time and effort to do so. The awareness of hunger, awareness of time since last meal, and the nocebo suggestion that such a thing as hypoglycemia in (most) normal people exists. It is a real thing with some medical problems, and a very few otherwise healthy people, but far overstated.
If we're into anecdotal levels of evidence, I eat once a day, and _feel_ the least energetic after eating, for 30-60 minutes.
Both glucose and insulin levels vary throughout the day, even in healthy people, so I don't see why blood sugar can't be "low", at least with respect to the individual's daily range.
To risk being that "hey, will you fix my computer/heath/car" jerk: I received this odd recommendation from my PCP: metformin for non-T2 diabetics is supposedly "dangerous" because "it lowers blood sugar." I was tolerating 1500 mg, no problem, with few side-effects other than losing weight faster (which was great). This doesn't make sense because there's nothing in the literature or warnings about it lowering blood glucose dangerously. So then how in tarnation would it (a now cheap generic, no less) in an FDA phase 4 clinical trial as the first and, so far, only "anti-aging" medication because it does something to promote healthier metabolic and other pathways?
Obviously my impressions are not data, but I thought I'd present them here because it seemed counter-intuitive to me that significantly restricting carbohydrates would result in high blood sugar levels.
First, you're not going to get really accurate measurements unless you've calibrated your meter against a set of venous-based lab blood draw results, across bands of glucose levels. Second, unless someone describes that they are taking their measurements on the same time of day each day, under the same contextual conditions, then it's tough to separate out the measurements independent of the context.
Example: someone says they take a measurement at 11 am every day. Sounds good, except if they don't reveal they drink a Starbucks sugar-coffee a couple hours earlier on their way into work, then it gives the wrong impression. On the other hand, if someone says, first thing in the morning, I wake up and take a measurement, eat nothing, only drink water, do no activity more vigorous than getting ready for work, and measure again one hour and two hours later, then you have a better baseline to compare against.
What you really want to see to establish your impressions as data are multiple keto-adapted people wearing Dexcom 5 CGMs, calibrating periodically with a meter that meets your typical glucose testing range with the greatest accuracy [1]. Then throw those people out of keto-adaptation, measure their ketones as they come back into keto, and compare their glucose levels.
I'm only a data point of one, but I've been keto-adapted so long that the Ketostix urine test strips can no longer detect my acetoacetate-based ketone levels (when you are keto-adapted long enough, you need to measure beta-hydroxybutyrate and not acetoacetate as ketone markers). I'm Type 2, but controlled without medication through diet and exercise. My one and two-hour post-prandials are below 100 mg/dL, usually below 90 mg/dL. I test upon waking up, two hours after waking up to measure dawn phenomena, then every 1-2 hours while water fasting until I break the fast, some time between 1100-1500h, when I use a six-hour feeding window to get in at least 200g of protein and as much leafy greens as I can handle. Then I test again before going to bed.
My keto diet level is 20g net carbs per day. Empirically, when I break out of keto to verify whether or not it is still a factor in my ongoing treatment, I can go as high as 150 post-prandial, and I get a headache. There are definitely diabetics who test higher on keto than off keto, but they are in the minority; it would be interesting to find out if the keto community participants who you read about are diabetics or not. I'm convinced that based upon my personal experience that was guided by the outcomes reported by other Type 2's however, that most (not all) pre-diabetic and diagnosed Type 2's can revert their condition and control it with significant lifestyle changes for a long time before resorting to medication at a very late stage in life, if ever.
[1] http://integrateddiabetes.com/2016-blood-glucose-meter-compa...
It became disruptive enough that I gave up IF on work days and now practise it only occasionally on holiday or weekends. That said my gut flora (see the new research on how gut flora influences the brain [1]) might be reliant on simple carbs and sugar (I have a coffee + pastry habit).
As somebody with a family history of addiction, I can confirm that I get all kinds of cranky without my carbs. Imho some brains just crave those constant dopamine kicks, losing all impulse control in the process, carb intake seems to play a role in that whole dynamic [0][1].
A couple of years ago I did some "metabolic balance" diet which was very low carb for a couple of months, mostly to treat my migraines. After initial irritation, I felt really good physically but I had a constant craving for all the tasty carb stuff, like white bread/noodles, wearing me down mentally. I don't think I could live like that for years.
I know for me, as a person with ADHD, I have MUCH better self control when I'm on keto then when I'm not. It's the main reason I stick to the diet.
I would not relate this point to serum glucose in any way, however.
Garbage in, garbage out as the saying goes. Proper diet will improve brain function and "self control".
From the paper:
"Resisting the temptation to eat the cookies presum- ably depleted an energy resource that could otherwise have been used to persist on the subsequent task"
To your point, the best way to diet then would be to avoid the temptation which would mean less use of glucose in the resisting of it.
This is talking about blood glucose levels, which is influenced by many factors, including glucose production in the liver.
The brain depends on a very small quantity of glucose to function - it arguably is more efficient with ketone bodies, for instance [1] - so covering not only glycolysis seems like an incomplete research.
[1] https://blogs.scientificamerican.com/mind-guest-blog/the-fat...
In case of ketosis [1], the brain mainly relies on ketone bodies for fuel.. I'm curious about how one's brain would perform in such state - judging by personal experience, the results would be very different.
When I eat carbs, most of my day is either "I'm so hungry I can't think", or "I just ate, food coma", and I'm only alert and maximally productive for the brief time after the food coma wears off and before I get hungry again. With keto, hunger and fullness are less distracting feelings that don't impact my attention as much.
Entering in ketosis was also an watershed moment, like an epiphany, with a sudden feeling of increased awareness. But it's hard to describe precisely, and I guess YMMV.
Recently I've noticed many articles on HN how sugar, carbohydrates, dieting, etc. affects the brain, gut, and overall human body. Ego depletion is now on my list of topics to research further because I want to know more about the human body. I always thought of my Kinesiology class in university to be important because it taught about the relationship between the health of the human body and its environment. I hope there will be more findings in the future so we can, in a sense, optimize ourselves. For example, based on this paper it seems that eating a snack when studying can lead to better processing information and staying focused.
[1] http://www.slate.com/articles/health_and_science/cover_story...
That aside, the gut (bacteria) / brain connection gets more and more fascinating. There's so much about our personal inner space that we have yet to understand. Amazing.
This was published in the Journal of Personality and Social Psychology, an APA Journal. You can find their peer review process here (under "The Peer Review Process"): http://www.apa.org/pubs/authors/new-author-guide.aspx
One of my favourite (peer reviewed) articles ever is: http://journals.plos.org/plosmedicine/article?id=10.1371/jou...
It would be great to see more summaries of papers from trustworthy sources. For computer science there is The Morning Paper [1] but I don't know what there is for other fields.
It would also mean that during a week-long fast self control should be almost impossible. Which it isn't, or it wouldn't last for a week or two.
I'm sceptical.
Since i started no sugar, no carbs diet my self control improved a lot, but that maybe self-deception
As your body begins to burn fat to create its own glucose, your self control should be very constant, never dipping to low from lack of glucose.
You don't get super-self control from a sugar high, so there is no benefit to high levels of glucose in the blood. Its just good to avoid the extremely low dips which someone in ketosis will never have.
http://www.slate.com/articles/health_and_science/cover_story...
https://en.wikipedia.org/wiki/Ego_depletion#Reproducibility_...
People cannot be in an excited state, like suppressed arousal of various kinds, without the body being involved.
http://www.indiana.edu/~abcwest/pmwiki/CAFE/Wang%20-%20Sweet...
(summary here: https://books.google.com/books?id=evc6jaibNd8C&pg=PT52&lpg=P...)
People repeating the fiction that "low blood sugar puts one in a bad mood" puts people in a bad mood when they haven't had sugar in the last twenty minutes. We evolved in a low sugar world and did just fine: or was everyone moody from 200,000 years ago until about a century or two ago?
We should use our reasoning ability to overcome negative emotions. We should also use our reasoning ability to master our desires, to the extent that it is possible to do so. In particular, we should use reason to convince ourselves that things such as fame and fortune aren’t worth having—not, at any rate, if what we seek is tranquility—and therefore aren’t worth pursuing. Likewise, we should use our reasoning ability to convince ourselves that even though certain activities are pleasurable, engaging in those activities will disrupt our tranquility, and the tranquility lost will outweigh the pleasure gained.
The idea of practicing will-power, learning to decline known-pleasurable outcomes as a form of practice, is a well tested idea in stoic philosophy. The practice seems to suggest that there is an energetic ebb and flow of indulgence that can be countered by refining one's ability to reason.
Oh, wait. That isn't how it works at all...
So, having a soda will replenish your ability for self control?
