Self-Control Relies on Glucose as a Limited Energy Source (2007)
fermatslibrary.com
fermatslibrary.com
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.
I'm sure that every professional reporter, whether science popularizer or something else, understands and takes seriously the need for obey the Hippocratic Oath in their own profession, too ("first, do no harm").
But.. it's not like the reporter isn't aware that the constraints they are subject to (much higher time pressure + less familiarity with the topic vs the researcher's low time pressure + intimacy with the topic) don't automatically absolve them of their responsibility to own any mistakes they make once the genie's out of the bottle. It mostly hurts their readership if they start employing non-facts once they add them to their repertoire of decision heuristics.
Sure science reporting is definitely a good force in the world for helping people make decisions over important stuff, but.. like.. the researcher's reputation is ruined for causing potential damage to academia, but a reporter doesn't have skin in the game and has little to lose if others trusted them.
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.
Thanks for your detailed refutation of this article. I pinboard'd the article, then read your comment, and un-pinboard'd it.
Your guess for the real mechanism is a depletable neurotransmitter. It brings up the matter of discipline - is it a consumable resource, or a buildable resource?
I think traditionally most people think of discipline/self-control being a limited resource. In the course of my own life, trying to manage habits( example, strength training, eating healthily) I find the less I have to rely on at-the-moment willpower, and more on habit, the more adherence I demonstrate. That leads me to think that discipline is a (precious) limited resource.
On the other hand, was listening to a Jocko Willink podcast episode this weekend, and he claims that exercising discipline leads to further capacity for more discipline.
I don't totally reject his idea, but it implies there isn't a limited neurotransmitter, but more some kind of positive feedback loop.
Truth is probably some kind of murky combination I suppose.
In the same way that "You" are not a monolithic entity, "You" don't pay attention to everything - take the old "think about your breathing" troll, which causes a redirection of attention to an otherwise autonomous function.
In this world, the role of "willpower" is in habit formation - doing something routinely enough that you train 'yourself' to do it automatically. So exercising this ability can help you train yourself to do it more easily - you're meta-training yourself to train yourself.
But the active exercise of will is by no means energetically free, and that's the origin of the original paper's hypothesis. I'd guess that this exercise of will is not especially amenable to alteration beyond gross physical trauma, but I don't think it has much to do with blood glucose.
Asking wastra to expand or show why he/she claims what they claim is fine. However, what I think people are taking issue with is the need for the aforementioned distinction in burden of evidence--it appears your comment on 'work and results' may be unintentionally misinterpreted in this way.
HN user wastra read a paper which is obviously rife with reports from weak chains of experiments, poorly reported and with borderline statistical significance.
Then, HN user wastra commented accordingly.
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.
It was after he fact that I found out this a commonly reported correlation. I wouldn’t be so quick to discount it as placebo.
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?
Fasting for health benefits is typically done for one to several days.
I'm not a doctor or the OP, but felt someone should respond to your question because of the risks.
http://www.slate.com/articles/health_and_science/cover_story...
https://en.wikipedia.org/wiki/Ego_depletion#Reproducibility_...
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.
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.
People cannot be in an excited state, like suppressed arousal of various kinds, without the body being involved.
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
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...
Also, they only fasted people for 3h. I've sucked a lot of junk out of peoples' stomachs who have had longer fasts, so this is not even a glycogenolisis phase: they could easily have been digesting food still. The participants were students, so maybe some had drunk alcohol, which, like a ketone is a two-carbon molecule...
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.
Oh, wait. That isn't how it works at all...
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?
So, having a soda will replenish your ability for self control?
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.
One way to do an experiment would be to fast someone for 48h (about when you completely run out of glycogen, and ketones start to ramp up from fat catabolism), and while fasting, infuse glucose, blinded, into them. I wonder whether people could tell whether they are getting IV glucose or IV saline, just by how they feel. Maybe someone already did this experiment.
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.
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.
And to answer your question . . . the difference is not subtle, so it's really obvious. For example, I was fasting last Sunday and did 6 hours of housework on a day I would normally play video games. I am fasting right now, and am destroying my work, doing chores on breaks, and cooking food for dinner. I can smell delicious food in the crock pot that I can't have for another four hours, and I do want it . . . but the desire is bothering me approximately as much as unwanted birdsong. Which is to say I barely even notice.
It's a heck of a thing. Everyone should try it at least once.
I've done 24 hour fasts several times and they basically just make me lose two days of productivity. One during the fast day because I'm completely worn down and another the next day as I'm still drained and takes a day of normal eating to get back to normal.
I stopped keto after a few months reaching my target weight, and was irritable and unfocused for 2-3 days.
It takes about 48 hours to deplete your glycogen, that's where "3 days" comes from - 2 to deplete glycogen then a third for immune system regeneration.
I say, give it a shot for sure. It's a lot easier to do once you've done it before. I practice fasting regularly.
------------
There appears to be significant research indicating a dramatic drop in inflammation, improvements in insulin signaling, and a near total “reset” of immune function with fasts of 3–5 days. Abnormal and or pre-cancerous cells appear to be pushed towards apoptosis, which essentially selects for healthy cell types. In total this describes a process which should (in theory) reverse many of the signs and symptoms of aging while reducing the processes that appear to be at play in autoimmunity and cancer.
. . .
In a process called apoptosis, also known as programmed cell death, cells that reach a certain age are programmed to commit suicide. While this may sound kind of macabre at first, the process constantly renews cell populations, making it essential for good health. But when just some cellular components need to be replaced, a process called autophagy kicks in.
The word autophagy, coined by Nobel Prize–winning scientist Christian de Duve, derives from the Greek auto (“self”) and phagein (“to eat”). So the word literally means “to eat oneself.” Autophagy is a form of cellular cleansing: it is a regulated, orderly process of breaking down and recycling cellular components when there’s no longer enough energy to sustain them. Once all the diseased or broken-down cellular parts have been cleansed, the body can start the process of renewal. New tissues and cells are built to replace those that were destroyed. In this way, the body renews itself. But it only works if the old parts are discarded first.
Our bodies are in a constant state of renewal. While we often focus on new cell growth, we sometimes forget that the first step in renewal is destroying the old, broken-down cellular machinery. But apoptosis and autophagy are both necessary to keep our bodies running well. When these processes are hijacked, diseases such as cancer occur, and the accumulation of older cellular components may be responsible for many of the effects of aging. These unwanted cellular components build up over time if autophagocytic processes are not routinely activated.
Increased levels of glucose, insulin, and proteins all turn off autophagy. And it doesn’t take much. Even as little as 3 grams of the amino acid leucine can stop autophagy. Here’s how it works: The mammalian target of rapamycin (mTOR) pathway is an important sensor of nutrient availability. When we eat carbohydrates or protein, insulin is secreted, and the increased insulin levels, or even just the amino acids from the breakdown of ingested protein, activate the mTOR pathway. The body senses that food is available and decides that since there’s plenty of energy to go around, there’s no need to eliminate the old subcellular machinery. The end result is the suppression of autophagy. In other words, the constant intake of food, such as snacking throughout the day, suppresses autophagy.
Conversely, when mTOR is dormant— when it’s not being triggered by increased insulin levels or amino acids from ingested food— autophagy is promoted. As the body senses the temporary absence of nutrients, it must prioritize which cellular parts to keep. The oldest and most worn-out cellular parts get discarded, and amino acids from the broken-down cell parts are delivered to the liver, which uses them to create glucose during gluconeogenesis. They may also be incorporated into new proteins. It’s important to note that the dormancy of mTOR is only related to short-term nutrient availability and not the presence of stored energy, such as liver glycogen or body fat. Whether the body has stored energy is irrelevant for mTOR and therefore for autophagy.
This is why the strongest stimulus to autophagy currently known is fasting, and why fasting alone, unique among diets, stimulates autophagy — simple caloric restriction or dieting isn’t enough.
Fung, Jason; Moore, Jimmy. The Complete Guide to Fasting: Heal Your Body Through Intermittent, Alternate-Day, and Extended (p. 151-153). Victory Belt Publishing. Kindle Edition.
You can also work directly with the author's foundation at https://idmprogram.com if you prefer.
With that said, he doesn't really talk about three to five day fasts much. It's kind of a suboptimal length. He talks about 24-48 hour fasts for weight and diabetes control, and 7-14 day fasts as cancer preventatives. The former is recommended multiple times per week, and the latter is recommended once per year. But again -- it depends on who you are and what your goals are.
My advice is just give 3 days an initial shot to see what it's like.
My first fast was 4 days when I was a teenager and it started as a joke "let's fast for the whole week then go to a buffet to see how much we can eat." That lead me to fast Monday-Thursday and we went to the buffet on Friday. Guess how much "clarity" that brought me? None.
A sense of clarity after three or four days is something a lot of people report -- certainly enough to say it is a real phenomenon. I don't know if the experience is universal, but it does seem to be quite common.
It's just that you are not speaking of fasting itself, you are speaking of a spiritual practice that incorporates fasting.
Besides, I have a ton of experience fasting, I fast very frequently, short fasts every week (1 to 2 days), long fasts every once in a while, when I feel like it. I enjoy the physical feeling of fasting. I was merely speaking about the very first time I fasted.
No, she is not (being married to her, I can speak with some authority regarding her intent.)
She does not fast as a part of a religious practice, but as part of a dietary one. And has likewise been reading dietary, not religious, guides to fasting. And it is a commonly reported experience for people to have a degree of increased focus/clarity on about day 4 of an extended fast. It can come in a religious/spiritual form, but can also simply be "man, I'm really on top of things today" -- as if the biochemistry of the body after 80-90 hours of deliberate fasting puts the brain into a mode of hyperfocus.
The other thing I've noticed is that I have much more patience with my kids (4 and 7) when I'm on keto. I can take them grocery shopping with me and they don't drive me insane, etc.
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.
However, I seriously doubt this is specific to self control. I would imagine performing any action that depletes glucose in the brain would have the same effects. Prioritizing tasks and deciding tasks to delegate are a couple I've read which are supposed to be very energy-hungry (I've been reading 'Your Brain At Work' recently and its mentioned in there).
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.