The problem with chronic cold exposure is that it makes one very hungry, a lot hungrier than usual, with the compensatory calorie consumption risking negating the intended benefit.
Anecdotally, my first 72-hour fast was revealing. Around the 48-hour mark my body aggressively signaled hunger, esp. for sugary foods. By the third day, however, hunger largely subsided, and at break I wasn’t hungry at all. For the following week the usual sugary suspects in my life went untouched. Subsequent 72-hour fasts were far more manageable, suggesting at least some component of adaptation.
My understanding is that this ability to adapt exists because intermittent hunger and cold were regular aspects of human life for much of our history, particularly in environments without reliable food access (pre-agrarian) or thermal protection.
Edit: for those wanting to try this lifestyle, everybody is different. do your own research before jumping into regular fasting or even cold showers. Max time without food I did was 6 days, since then t it he max is 72 hours. Do blood work regularly and if you drink coffee be aware that caffeine withdraws are painful.
It's mind-boggling to me that multiple "one meal" days don't incidentally happen to everyone over the course of a year.
I would think most people have those days where they skip breakfast and lunch due to some or other exigency and only get to eat dinner.
By midday I'm on an adventure. Some days, it takes me in a direction where it makes more sense to skip lunch than to stop and have it.
When I'm hungry and it's convenient, I eat. When I'm not, I don't.
It's almost never the case that I'm hungry for a meal three times a day.
I've successfully used caffeine pills (e.g. some NoDoz brand products) for coffee replacement to avoid withdrawal symptoms.
Specifically I used caffeine pills to give up coffee. I found it easy to taper down caffeine usage to zero by using a standardised dose size.
Additionally pills are a habit change which helps me stick with a plan. I have tapered down using instant coffee but I found that was a little harder to police myself.
What is funny is that, at least for me, the sensation of hunger is strongly conditioned by whether there really exists a possibility to satisfy it.
I eat 2 meals per day and during the time between them I am not hungry, and if I were hungry that would be futile, because I intentionally do not keep in my home any kind of food that can be eaten instantly, but only raw ingredients that I must cook before eating.
After I cook my next meal, I have to be patient and wait some time for the food to cool down. During that time, I become suddenly very hungry and like you say, I find it difficult to continue to work at the computer or at whatever I was doing, as my thought shifts to the food I am waiting to eat.
In the past, when I kept food that could be eaten at any time, without preparation, I became frequently hungry and it was hard to resist to the temptation of having a snack.
The breath thing is unavoidable as far as I know.
Even more surprising is that fermentable fibers get converted into short chain fats by bacteria in the gut that are ultimately metabolized as ketones, so a diet high in those can induce ketosis even with a high carb diet. Some herbivore animals are always in ketosis, and some carnivores are almost never in ketosis unless they are starving and can’t find protein.
More generally, it seems inconsistent to assume someone can voluntarily tolerate significant cold discomfort while being unable to manage similar degrees of hunger discomfort.
It’s like my brain has retrained itself to ‘just get over it’. It was quite something
If it does negate the benefit than that would suggest that the entire benefit from the beige fat is from putting the body in a calorie deficit, and you would then expect the exact same effectiveness from calorie restriction. A quick search shows that there does seem to be an anti cancer therapeutic benefit from calorie restriction, so this seems at least plausible.
So this raises the research question of if increasing calorie intake to keep weight stable completely negates the anti-cancer benefits of increased beige fat or not. I’m curious if that has been investigated yet.
In the past it seems the consensus was that since cancer cells need more fuel than regular cells, starving them is beneficial in combating it.
But recently it has been discovered that some cancers can grow better with ketones.
So it seems that some cancers benefit from fasting while others are starved from fasting.
https://onlinelibrary.wiley.com/doi/full/10.1002/cam4.5577
edit:// and the article has imho nothinh to do with autophagy. Its about beige fat cells eating stuff away from cancer not autophagy wich happened in the innercell. And if you go into caloric deficit you could burn away those beige fat cells that "heal" the cancer.
I was only raising questions this research and discussion made me curious about, not making any concrete claims.
Although the idea of calorie restriction as a cancer treatment is something still actively debated and researched, I personally doubt it is very useful, or likely to be the main mechanism here in the connection between beige fat and cancer, but it is a possibility to at least be ruled out experimentally in the context of the comment I replied to, which is why I mentioned it anyways. One major concern with calorie restriction in humans but not rodents is that it shuts down your metabolism by limiting t3 thyroid hormone production whereas cold exposure ramps up metabolism by uncoupling mitochondria to produce heat. You are correct that the body can shut down processes and systems that might be important for fighting cancer, in response to calorie restriction.
I am a researcher that studies metabolism, and actually think the prominent focus on fasting and calorie restriction as a potential medical cure-all has been mostly a dead end, that people were mistakenly led down largely as a result of these fundamental differences between rodent and human metabolism.
That was the part that confused me.
"If it does negate the benefit than that would suggest that the entire benefit from the beige fat is from putting the body in a calorie deficit, and you would then expect the exact same effectiveness from calorie restriction"
As far as I understood the paper its beige fat that can eat away food from cancer and not white fat. And afaik calorie restriction doesnt augment beige fat. My error was thinking you meant calorie restriction while having white fat but you meant with beige fat? And yes this makes sense.
And I thinked autophagy because this is the main "thing" happenkng while fasting which is not burning body fuel
thanks for the answer
Yes, autophagy does ramp up during fasting, but it's just one of a number of different physiological changes that occur during fasting.