[MeImCounting]

Just gonna put this out there that this is dangerous, faddy advice. Fasting is a road to eating disorders and is much harder on your organs than eating nutritious food.

If it "works for you" thats fine but I hope someone will always put it out there that fasting is dangerous, unsupported by evidence and more dangerous than you can know.

Fasting gives you a dopamine dump to give you the energy to find food. Not because it is in anyway good for you. Fasting makes people feel good after ending the fast because your body is relieved to no longer be starving. These dynamics are well understood in the context of eating disorders where "health fasting" is a well known symptom and excuse.

It's crucial to note that most studies on intermittent fasting have been short-term and conducted on animals, focusing on immediate changes like glucose levels rather than long-term health outcomes. This lack of extensive scientific data calls for caution in adopting intermittent fasting, especially for individuals with specific health conditions or vulnerabilities.

[nerdponx]

2-5 day fasting seems extreme. I think most intermittent fasting recommendations are more like "skip lunch 3 days a week".

[xboxnolifes]

Usually it's more like skipping breakfast and not snacking after dinner. Skipping lunch isn't much of a fast if you're eating breakfast at at 7am and dinner at 7pm. But eating dinner at ~7pm and having your next meal be lunch is ~16 hours without eating.

[xk_id]

> Fasting gives you a dopamine dump to give you the energy to find food.

The hunger-hormone ghrelin actually has substantial and broad benefits to health, including an evolutionary sharpening of cognitive functions [1], albeit possibly at the cost of a narrowing of focus to food-related topics.

The fast/feast cycle was recently found to recapitulate in humans the improvements in health biomarkers typically observed with caloric restriction, with less detrimental effects on the immune system and bone density [2].

Anyway the line between dietary restriction that improves health and an eating disorder is a fine and dangerous one. The difference is made by meticulously monitoring your micronutrient requirements to avoid any deficiencies. Assuming otherwise optimal nutrition, caloric + protein restriction is consistently associated with improvement in health biomarkers. But long-term human trials with hard endpoints like longevity and suitable controls don’t exist and are impractical.

[1] https://pubmed.ncbi.nlm.nih.gov/27993602/

[2] https://www.cell.com/cell-metabolism/fulltext/S1550-4131(19)...

[MeImCounting]

There are certainly complicated physiological effects caused by fasting however the heterogeneity and limited number of studies make it difficult to draw definitive conclusions

Mental deficits are associated with fasting across a review of a variety of studies

https://pubmed.ncbi.nlm.nih.gov/34595721/

Fasting can also cause other mental issues: "Additionally, fasting was found to be associated with alterations in mood, including worsened mood, heightened irritability, difficulties concentrating, and increased fatigue, as well as an increase in depressive score in mentally healthy humans"

https://www.nature.com/articles/s41598-022-11639-1

All in all it remains highly suspect that fasting has anything but long term and short term negative effects. As I said in another comment it makes sense to me that so called "health fasting" tends to be more common among people who are already vulnerable and at risk for disordered eating. I will continue to spread awareness about the link between "health fasting" (as well as other health and diet based fads) and actual life threatening eating disorders.

There is a huge lack of research into eating disorders generally and even less research into the interaction of health fads and eating disorders. I encourage everyone to advocate and support any and all research in this area to combat misinformation spread by "health" gurus and companies looking to make a quick buck.

[xk_id]

Well fasting is hardly a consumerist conspiracy, as that would be a contradiction.

It’s likely that the downsides are a necessary trade off for a longer lifespan. The body reduces its metabolism in order to conserve resources and survive long enough until access to sustenance returns. The most dramatic change is the loss in libido; maintaining an active reproductive system has significant metabolic demands, so they are deprioritised. It’s possible that what we consider “healthy baseline” in the contemporary age of caloric abundance is actually a hyper-active state that accumulates rapid damage and dietary restriction brings metabolism down to a frugal and entropy-conserving state.

Edit: those two fantastic papers should provide you with all the help you will ever need in your efforts:

http://www2.hawaii.edu/~vitousek/CRAN2.pdf

http://www2.hawaii.edu/~vitousek/CRAN1.pdf

[MeImCounting]

Critiques of caloric restriction (CR) studies include issues with control groups in animal research where these groups might eat more than usual complicating comparisons. Also, CR's benefits could vary based on eating habits and may not apply to everyone. There's a concern that extreme CR can weaken the immune system among other issues like bone density loss etc. The overall impact of CR on health and longevity clearly needs more research to be understood.

While its undeniable that some of the strains of mice and fruit flies did live longer, extrapolating that to humans and associating that with "health fasting" is questionable at best. If this becomes a viable technique for human health and life extension it ought to be undertaken in a supervised and managed way with the assistance of health professionals. Not sold as a magic treat-yourself cure for all ailments on the internet.

All in all CRL outside of an academic and scientific setting is almost certainly just going to spread dangerous misconceptions about health and our bodies.

> "Well fasting is hardly a consumerist conspiracy, as that would be a contradiction."

No fasting clearly isnt but most of these "health fasting" diet types also shill other dangerous "health" advice from juice "detoxes" to radioactive "aura cleansers"

About that "CALERIE" trial: "many of them had BMIs that fall in the overweight category at the start of the trial. This means that any health benefits observed cannot be fully decoupled from the weight loss most participants experienced on their restricted diets. It is already well-known that going from being overweight to a healthy weight has a positive impact on the body; however, the trial results do not clearly answer the question of whether metabolic changes due to calorie reduction beyond a normal diet can improve health. Moreover, the trial was too short to determine the long-term effects, good or bad. "

https://sitn.hms.harvard.edu/flash/2020/can-calorie-restrict...

So like I said above portraying this as somehow proven to be healthy in humans is a vast oversimplification of a complicated field and really isnt related to "health fasting" at all

[xk_id]

Uhh. This is so strange. I now realise that you're not really interested in engaging attentively, you just have a bizarre fixation with fighting against fasting.

I already brought up osteopenia and the effect on the immune system two posts ago. Furthermore, they are discussed at length in 2 of the sources I linked. Yet you repeated this point as if it was something completely new. It contributed nothing to adding further context and moving this particular conversation forward. I also never brought up the CALERIE trial (which btw had an average BMI of 25 and excluded anyone abouve 28); however, I did post a source to a different trial in healthy (normal weight) people, which you didn't engage with. You actually didn't engage directly with a single point of mine.

All in all, it seems I'm just wasting my time expecting a nuanced conversation that I can learn something new from. You're just eager to repeat a memorised script.

[MeImCounting]

Youre right I havent really engaged with the specific sources you cited and to some extent probably wrongly assumed you to be advocating health fasting as a cure-all. I apologize this was probably not a productive way to go about having this conversation.

This is partly a knee-jerk reaction as I have had subjective experiences with vulnerable and at risk loved ones and acquaintances falling for faddy scam health advice and triggering underlying EDs and other health problems. It is way more common than you think.

While I dont have any sources or other good information to provide I can say that I think we really need more research into EDs hereditary nature, long term health effects, psychological effects among other factors before this technique begins to be widely used.

Like you said earlier "the line between dietary restriction that improves health and an eating disorder is a fine and dangerous one." I really think this is very true. Specifcally I worry about people who dont know they are genetically predisposed to EDs and attempt to do health based dietary restriction. This could be catastrophic for those individuals.

[giraffe_lady]

I don't encourage people to fast but it's also not true that it's unsupported by evidence. It's an ancient and widespread practice in nearly all of the major world belief systems. Billions of people fast, and there is a massive cross-cultural body of writings about the effects of it.

Which is not the same as modern peer-reviewed medical study, no. But it's not "no evidence" either.

[MeImCounting]

https://clindiabetesendo.biomedcentral.com/articles/10.1186/... https://centerfordiscovery.com/blog/the-dangers-of-intermitt...

I take the stance that health fasting is vastly different in effects from fasting as a religious observance. For instance the frequency and duration of so called "Health fasting" among other factors including the fact that "health fasting" seems to self select for people already at risk of disordered eating.

[giraffe_lady]

Yeah I think I agree with that. I'm skeptical of fasting outside of a specific tradition and guidance. But don't like to see the value of those traditions dismissed either.