The surprising cause of fasting's regenerative powers | Hacker News Reader

The surprising cause of fasting's regenerative powers

nature.com

47 pointspseudolus62 comments

For those potentially concerned about cancer risk from breaking fasts, from the article itself:

> Researchers should always be concerned about anything that could cause cancer, but Valter Longo, a biogerontologist at the University of Southern California in Los Angeles, says that mice with the tweaked genes were “almost doomed to get cancer”, and that the slight rise in risk found in this study might not be applicable more broadly. For example, he points to a study he published in 2015 that found a 45% reduction in abnormal cell and tissue growth in mice that fasted compared with animals that did not.

The mice that developed precancerous growths were genetically modified to be prone to such cancerous development.

Yeah, all the research I've read says that fasting is actually preventative when it comes to cancer -- and possibly assists with starving out cancer cells during treatment of the disease.

I read all sort of contradictory "scientific facts" about this subject. By the end of the day, listening and observing your body will provide you the right answer.

Sure...but an interesting recent-ish development is that you're not only listening to your body, but to a enormous microbiome that is also signalling you towards its own ends (it's sugar, they always want sugar).

Here's a paper that talks about the pathway: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4367209/

Not really about the sugar point. At times people crave savory or something high starch+fat based. For instance, little kids generally tend to crave for very sweet things but at times prefer something like pizza or pasta over something sweet (this is based on a personal second-hand observations). This is also the case for humans, for example during cheat days that people don't simply eat sweets (for example Dwayne Johnson finishing up something like 12 pizzas as one of the things on his cheat days).

Everyone is different that's for sure. I haven't eaten breakfast since I'm a teen and I mostly eat one meal a day for the last 10+ years

Everybody talks shit about fasting but nobody even bat an eye at "you have to eat three times a day, every day, at the same time, everything else is obviously wrong", which is at least as ridiculous

Around here, the five mealtimes are morning-meal, 9 o'clock snack, midday-meal, 4 o'clock snack, and evening-meal.

On the other hand, I've been in a resort where they announced "merienda will be served between X and Y o'clock", which scandalised my local friends, who wondered aloud who'd ever heard of such sacrilege as eating merienda according to a clock and not your stomach.

My impression of historical practice is that people who had to go work in groups, in fields (or later in factories), tended to hew to traditional mealtimes. (there's a nice discussion somewhere on HN about how you don't want to stay in the fields between noon and one, or the "noonday witch" will get you...)

However, those who could afford it simply ate whenever they felt like (in at least two asian countries I know, it's considered a faux pas if there is ever a moment during the day when the main table doesn't have some sort of food on it).

The story I heard is that in the western context it was Louis XIV* who instituted mealtimes for rich as well as poor: his court was so large and so elaborate that logistics demanded the kitchen no longer be open, as it had been under previous monarchs, for courtiers to swing by at any hour they felt like grabbing some grub. True, or "Just So"?

* later, in the waning days of Austria-Hungary, the protocol at court dinners was that one did not continue eating dessert after the Emperor had finished with his. Of course, he had also been served first, so at some precedence level it must've always been a throw of the dice, whether one would even get served any Kaiserschmarrn before it was time to down forks.

Given that fasting is enshrined as a order in many belief systems, it seems like humans needs external motivation to ignore their body's complaints and fast for positive effects.

75% of adult in the west are obese or overweight because they listen to their body...

What we call fasting today was the defacto lifestyle for hundred millions of years. The current three meals a day pattern doesn't even register on that scale

thats not always the right thing to do. drugs can mess with what you feel/want for example. we meatbags do have really bad sensors at times.

Is there a name for the phenomena encountered with this particular response?

Specifically, I’m talking about when discussing extremely complex systems, ones that we don’t have full understanding of, there’s this tendency at a certain point of complexity to throw your hands up and say:

“because we can’t understand all of it perfectly then we can’t understand any of it and so just rely on these exceptionally loose grained impossible to define heuristics that have no comparability reference or baseline or anything meaningfully objective”

It’s like completely abandoning the concept of science measurement and just going full in with nothing matters we can’t measure it so do whatever you want.

Is it a failure of communication or is this an actual cognitive pattern that we can define?

It seems like a basic implementation of the all or nothing fallacy

I present to you the Wikipedia List of Cognitive Biases: https://en.wikipedia.org/wiki/List_of_cognitive_biases#Egoce... . There is a lot of overlap on a topic like this, but probably something like the "Illusion of validity".

That being said, listening to your own body is not a bad strategy. The nervous system evolved in tandem with this particular extremely complex system and is arguably purpose-built to keep it in good working order.

| listening to your own body is not a bad strategy.

Is it this strictly true? Are people that are overweight not just "listening to their body" when they overeat? I feel its not as simple as that. If we always listened to our bodies we would never exercise beyond the first instance of becoming tired for example.

The existence of things like psychiatric meds imply that the answer to "listen to your own body" is not universally yes.

Engineering.

Is there a name for the phenomena encountered with this particular response?

Specifically, I’m talking about when discussing extremely complex systems, ones that we don’t have full understanding of, there’s this tendency to ignore the huge gaps in our knowledge and deny that individuals can know anything objectively about how their body responds to things, even though science has no explanation for it…

This is a curious statement

>ignore the huge gaps in our knowledge and deny that individuals can know anything objectively about how their body responds to things, even though science has no explanation for it

You’re claiming that

There are “huge gaps in our knowledge”

And that (some group) denies that “individuals can know anything objectively about how their body responds to things”

Implying that the latter satisfies the first

This is precisely what I’m asking about

You’re suggesting that a less specific and less measurable vague notion is more predictive than the current state of the art in measuring bodily

On what evidence do you rest such a claim?

I rest it on my own personal experience and that of many others, which you don’t seem to accept. Nevertheless, here is just one example of what I’m talking about.

I spent over a year with daily terrible headaches. I suspected they were related to my thyroid medication not being correctly dosed, as they started immediately after a new bottle of medication arrived, and closely resembled headaches I had had related to dosing issues in the past. The measurements and latest “scientific" knowledge said my dose was fine, so various doctors had me try all kinds of different things. I even tried a chiropractor. (I’m not a fan of them in general. Mostly crazy kooks in my experience.) I finally found a doctor that suggested my dosing was wrong, changed my prescription, and the headaches went away immediately. This doctor (and many others), based on the experience of many thousands of patients’ experiences, believes the current scientific consensus on thyroid hormone dosing is wrong. And everybody knows there is a huge gap in our knowledge around hormones in general.

So there you have it. I could give other examples, but they would be second hand, rather than first.

Oh, and then a year after I finally got this solved, I got a letter in the mail that the batch of medication I had received at the start of this all was being recalled... for being wrongly dosed.

Science is a good guide, on a population level. It is up to the individuals to customize the guidance to what works for them.

Faith based reasoning.

A pox upon it's house!

It's well and good to listen to your body. Observation and insight is humankind's great boon. But man, the science nihilism & belief you can just think about it and come up with better understanding than the world's greatest doctors & researchers is astounding & a massive boat-anchor that threatens to drag humanity down below the waves. Awful.

Complexity-matching.

You have one complex adaptive system with a simplified interface to another complex adaptive system and you leverage that to understand the first, where trying to reduce it to a toolkit that you can internalize is impossible due to the finite nature of your cognition.

OP is like your ancestors trying to predict the arrival of game in the spring and relying on a certain flower blossoming.

Yours is trying to arrive at a working calculation involving the time from the winter solstice combined with the daily sun exposure, thermal gain, precipitation, and biennial changes in major weather patterns, etc, leading to the possible but not certain generation of a new complex system that must be sustained by a population of humans and might not ever work as well.

In many instances, your perspective is the more questionable one.

In effect you’re making a claim that in the general case, less systemic precision is preferable because more precision is brittle

However you cannot know the relative brittleness apriori and you have to have a consistent measure that you’re comparing to

Like it seems that you’re suggesting a loose grained low variance forecasting model will only find high likelihood inferences and filter everything less impactful - making it more robust

However experiments regularly destroy previous concepts by the merging of conflicting variables - this is hegelian synthesis, or popperian falsification

So foundationally that thesis is flawed because it implies no system improves from additional observation - it gets more brittle. The entire theory of the firm, monopoly efficiencies etc… are a counter example disproving this logic

That said, all systems are coupled, so if a complex system is optimized around a narrow saddle point then it tipping into a new state may perturb other coupled models which cause cascading adjustments - that’s not more brittle by default. It means you have to observe more coupled interactions and not overestimate likelihood you can’t experimentally validate with a functional system.

You strawmanned my argument into brittleness, but there are significant other options such as that there may not be sufficient technological reach to even construct a reasonably accurate complex system.

I did not say things can only progress into brittleness, you invented that so you could have something to argue against.

Underfitting?

The response to 'science is confusing' should never be 'ignore science'

Fair, though I think a charitable read of the advice would be not to wait for a complete consensus in science before living your life.

I don't think anyone has ever said you should put your life on hold until nutrition science is settled?

Fair. My experience with people that read all sorts of contradictory studies, as the OP mentioned, are more on hold than makes sense.

I guess people can take these headlines about nutrition research a bit too serious. Doesn't help that there's so much vested interested involved in what people chose to eat.

I do think trying to make sense of it is a great exercise in critical thinking. And I enjoy one thing about this: nutrition is about complexity. Trying to nail down a perfect diet or 'super food' is akin to looking for a silver bullet in software development.

Also a great opportunity to think about unintended consequences and consumerism. Think about the impact of quinoa fads on Peruvian farmer communities.

If anything, nutrition science is a masterclass in complexity. That's probably why these cliche 'oh nutrition science is so full of contradictions' rub me the wrong way.

Agreed. Using a metaphor of hiking a mountain generally works for me. Most steps you can make from any given spot are generally not that impactful. And sometimes you do have to make a lot of neutral steps in order to get on a path that will take you farther. Sometimes, you even have to backtrack. And all choices are highly dependent on where you, specifically, are.

It's not "science is confusing", it's "science can't tell us anything definitive about this subject yet". Science is a process, not an artifact. Finding two conflicting papers on one subject and deciding to ignore both is not "ignoring science", it's ignoring two conflicting results that science is still working through.

Science can never tell us anything definitive about anything by definition. Science is trying to contradict previous results to refine and nuance our understanding.

Confusion is essential to the process and pretending like something hasn't been published because it contradicts previous results is... well, anti scientific.

Pointing out nutrition science is full of contradictions is kinda tired. Learning about research biases and epistemology is probably more productive.

Sure. But there are many things that science has come to a pretty good idea about. Nutrition is miles away from that. The only truly established theories we have in nutrition are how to cire vitamin deficiencies.

Everything beyond how to avoid scurvy and the like is currently just noise. For every paper that finds an effect in nutrition, there is another paper that finds the exact opposite: so, there is no actionable advice to take from this. Maybe in 50 years when things have settled.

Edit: I don't mean to say that this isn't part of science. It's a normal part of the process. But when we're just starting to experiment scientifically in such a complex field, it's normal that we just don't know a lot and our theories are just bad at the moment. They will get better, but there's no point whatsoever in following a theory that is not yet well confirmed by experiment.

You really seem to be speaking from a place of ignorance here, with all due respect.

There's quite a lot we know about nutrition. You may be conflating the whole field with the type of studies that grab the attention of journalists.

Care to give some examples of well established theories in nutrition? Especially ones that can be used to inform a balanced diet?

https://online.stanford.edu/courses/som-xche0001-nutrition-s...

Yeah, which is why you should always eat leaded paint. How can something so sweet be bad for you?

I tried one meal per day for three weeks and I had to quit because my heart would start racing after my meal.

Really bizarre. I couldn’t find any information.

Interesting, increased heart rate after eating is not uncommon [1]. Could be a sudden influx of glucose after fasting kicking a lot metabolic functions into gear.

[1] https://www.healthtoday.com/be-healthy/heart-health/why-does...

I haven't had that experience, but I usually do longer fasts.

My go to for this would be electrolyte levels, which can vary heavily depending on water intake, diet, exercise, supplementation, etc.

Here's some journal articles I found based on a quick search.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1364615/ https://pubmed.ncbi.nlm.nih.gov/8777833/ https://link.springer.com/article/10.1007/s002280050682

Be interested to hear if something in one of those pops out at you.

Were you supplementing with electrolytes while fasting? Don’t have any studies at hand right now, but fasting apparently causes you to quickly lose fluid and electrolytes.

I recently started doing 5:2 fasting and noticed on the day after fasting that I tend to get bouts of pretty bad orthostatic hypotension. Supplementing with a zero-calorie electrolyte on fasting days and the day after helped mitigate this.

I lost 15kg by tracking calories and eating one meal a day in the evening. The rest of the day was filled with coffee and an apple for lunch.

I've pretty much stuck to one meal a day now. Lunch is still something light, like a protein bar or an apple. The only time I really eat breakfast now is if I'm on holiday and it's included...

Probably the sudden spike in blood sugar from carbs. Your blood sugar was lower the rest of the day, so the carbs all at one feels like if you are three sugary candy bars in a row.

I've had a lot of success with OMAD for weight loss and improved attention, but it's a lot more protein and fats and veggies. And I make sure the starches I eat are slow-digesting like pasta, not fast-digesting like bread or any sugary desserts.

So what's the surprising cause ? I couldn't find it after skimming the article twice.

> Breaking a fast carries more health benefits than the fasting itself, a study in mice shows1. After mice had abstained from food, stem cells surged to repair damage in their intestines — but only when the mice were tucking into their chow again, the study found

Literally the first paragraph

I still don't see the cause. Eating is the cause ? How is that surprising ?

You can have a finding without knowing the underlying cause. As an easy example, see gravity.

In this case, the presumption is that it isn't necessarily the eating? It is specifically the sequence of fasting -> eating. As just eating with no fasting involved does not trigger this. Similarly, just fasting did not get this response, but it primed the mice so that their next meal did.

Yeah the title is "The surprising cause of fasting’s regenerative powers", I wanted to know about the cause. The article doesn't mention it.

Clickbait article.

Apologies on missing this. Fair. I was interested in the link and the idea that there is something there, even if we don't know what.

The surprise is that the benefit isn’t gained until you start eating again. It’s not during the fast that good things happen, apparently.

The article actually seemed to suggest that eating after fasting increased the chance of "precancerous growths", which seems like "bad things".

And then refuted that with a different study at the end. Weird.

tldr; positively impacts stem cells making them more effective at repairing damage

Which also lead to tumors as polyamines are involved in cellular division.

.. in mice.

Interesting post to wake up to when I'm 7 days into a fast.

Glad to be getting back into extended fasting, sad that I, again, have the body type that makes it somewhat of a requirement health wise.

The actual paper (paywall): https://www.nature.com/articles/s41586-024-07840-z

Interesting, but I would be careful to generalize from mice studies

Are there any other studies in the topic except on mice?

Generally the answer is 'no' to that question.

Medical ethics tends to prohibit it, especially in a clinical setting. It's seen as doing harm to the patients, which physicians tend to frown on.

I've even heard of some papers on fasting, retrospectives -- which I think aren't technically studies but an aggregation and analysis of patient data, collected from events that have already happened, which patients voluntarily undertook -- that were banned from journals because the results may have 'encouraged harmful behavior.' Don't have any sources on that and it's a memory from like 6-8 years ago though.

> After mice had abstained from food

Yeah, right, mice abstained from food. Mice don't abstain from food. You didn't feed them!

Nice catch. This is a step worse than hiding the actor as in "the mice were sacrificed." It flips the whole script as in "the mice (heroically) sacrificed themselves (for science)."

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