5 ms·

I'm not sure what you mean by an "instance", but there will likely be variations in how quickly people respond to metabolism, and also depends on what you're ea

I'm not sure what you mean by an "instance", but there will likely be variations in how quickly people respond to metabolism, and also depends on what you're eating during the fast. One possible mechanism is that the muscles of the people fasting are more able (either through genes or exercise) to burning fat, meaning that you need to convert less fat into glucose. I'm not a biochemist (I've mainly read Good calories, bad calories plus various primal/low carb blogs) but it seems pretty straightforward (fat -> fatty acids -> acetyl-CoA -> ketones): http://en.wikipedia.org/wiki/Ketosis http://en.wikipedia.org/wiki/Ketosis Feeling sick on a caffeine detox is likely to just be withdrawal, and/or the "low-carb flu".

beagle3 14y ago
> I'm not sure what you mean by an "instance" I defined it earlier: specific person, at a specific fasting period (by which I meant contiguous period). > also depends on what you're eating during the fast. I don't think we're talking about the same thing. "fast" says "what you're eating" is nothing.
- anthonyb 14y ago
  Eating nothing for three weeks?! That's stupid and dangerous. You're putting your life at risk from heart attack and kidney and liver failure (and other people's, judging from your comments in this thread).
  - beagle3 14y ago
    > Eating nothing for three weeks?! That's stupid and dangerous. To quote other people on this thread - "citation needed". I've done this more than once, actually, and I know others who do too. Yes, I have eaten essentially nothing for three weeks. No, I wasn't putting my life at risk of anything, though you may believe what you want -- did you notice that I'm not the only one who posted about long fasts? You just assumed everyone was eating, but we use "fast" literally, not as a codeword for "calorie restriction". Although I had the references to support that it's healthy, I did do bloodwork a couple of times through, and at the end, it was -- in fact -- much, much improved. For example, my B12 levels went from -2 sigma to +2 sigma. (If this sounds impossible to you, read the wikipedia entry about B12 - the general "knowledge", even among doctors, about B12 is unbelievably incorrect). My doctor, who is a reasonably open minded MD, looked at the results and said "just make sure you start eating when you are feeling hungry". That happened 21 days after I started. He wasn't worried after looking at my bloodwork. If you're healthy at the beginning, irreversible damage starts around day 40 (but is very swift at that point). There are quite a few people in India who do 30 days every year for religious reasons, and suffer no ill effects -- and have been doing this for centuries.
    - anthonyb 14y ago
      Your b12 will be up because your body is cannibalising its tissues to stay alive. That's your liver, kidneys, etc. and it doesn't mean that you're healthier. Given that you don't know that, and earlier on you didn't know what ketosis is, I'll take your dietary advice with a large grain of salt...
      - beagle3 14y ago
        Wow. I mean, you have all the answers! I did know what ketosis is. But ketosis DOES NOT induce acetone breath in 99.9% of the population*time - which is what I understood you asserted. Look it up. Really, look it up. And you better read about b12. You are radically misinformed. Not that I care - it's your health that will suffer. Really. Look it up.
        anthonyb 14y ago
        No, you go look it up: http://en.wikipedia.org/wiki/Vitamin_B12#Foods http://en.wikipedia.org/wiki/Vitamin_B12#Foods. What's the top source of B12 on that list? Now, given that you're not eating beef liver, which liver do you think is providing all that B12? Stupid. Dangerous. Edit: Thinking about it, I'd put fasting for 3 weeks in the same class as running a marathon: if you can do it, you're probably healthy. Actually doing it though, is not healthy at all.
        beagle3 14y ago
        No, you read the article you quoted: Under "Foods", the section you linked: ... Ultimately, animals must obtain vitamin B12 directly or indirectly from bacteria, and these bacteria may inhabit a section of the gut which is distal to the section where B12 is absorbed. Under "synthesis and industrial production": .... Neither plants nor animals are independently capable of constructing vitamin B12.[30] Only bacteria and archaea[31] have the enzymes required for its synthesis. And a little later: .... The total world production of vitamin B12, by four companies (the French Sanofi-Aventis and three Chinese companies) is said to have been 35 tonnes in 2008.[40] Most of this production is used as an additive to animal feed.[41][citation needed] It doesn't matter what the top source on the list is if you can have it synthesized in your own body. Which I now do way better than I could before my first fast. You know why cow liver has B12? Because cows are fed B12 these days so that beef liver would have enough B12 for human consumption! That's so ridiculous and inefficient it is sad. You know why B12 synthesis is so horrible among both humans and livestock today? Because of how much we use antibiotics. And there's also another surprising finding: The human body (and most other mammals as well) have a cache of the organisms required to synthesize B12 and a host of other useful stuff. It's called "The appendix", you might have heard about it. The body will release these organisms from its cache under ketosis lasting more than a few days, to replenish and revive the useful colonies. Nature is very smart like that -- a few days of fasting are completely normal when your food source dries up. So the body uses that period to do maintenance. [I'm not going to spend time looking for the refs right now, partly because I no longer have access to full article texts, and mostly because I don't have the time; But this was hypothesized decades ago, and AFAIK conclusively proved something like 5 years ago, although it's not really well known so far even among professionals who should know better] > Stupid. Dangerous. Religious, is all I can say about your responses. You know things to be right, like it is dangerous to fast, or (I assume, although you might already be enlightened about these subjects) that dietary cholesterol is bad for you (it's almost independent of blood cholesterol, which is an important marker, though not a cause for disease), that you shouldn't eat more than a few eggs a week (nonsense; eat as many as you want - 20 a day is not unhealthy), that low-fat dietary intake is good for you (it's not), that butter is bad for you (it's excellent for you if it's from healthy grass-fed cows), that weight change is exclusively a result of caloric balance (only in the useless tautological sense), that you should minimize salt intake (too little is as bad as or worse than too much), or that cushioning is good for your feet and that's why sports shoes have them (they're bad for you except for very specific circumstances; they were championed by marketers, not researchers). I try to challenge my beliefs and understand why I have them. I often (way too often, unfortunately) find that things everyone (including myself) takes for granted are actually better classified as "wrong leaps of faith" or even downright superstitions than science. When someone contradicts me (and it's something I haven't researched and do not have a good basis for my beliefs), I try to start again from a blank slate, rather than find support for what I believe in (because you always can do that, regardless of how wrong you are). > Edit: Thinking about it, I'd put fasting for 3 weeks in the same class as running a marathon: if you can do it, you're probably healthy. Actually doing it though, is not healthy at all. I don't think this analogy is proper. Evolution surely did prepare you to run short distances. Evolution did not prepare you to run a marathon - you have to practice to be able to do that, regardless of how healthy you are - and I agree it is probably not healthy (although I have no support for that - for all I know, done properly, it might be super healthy). Evolution did prepare you to survive if your food source dries up (at least for a short while), or if you sprained your ankle and can't chase your prey or climb the tree to get food. In fact, it's apparently piggybacked some maintenance jobs on this period because (at least pre- agriculture) they were guaranteed to happen relatively often. You may argue about how long that "short period" is - evidence collected mostly from religious fasting is that it is around 40 days when you are healthy. > if you can do it, you're probably healthy. I disagree in general, but there's an important point here that I must stress - it would probably have been unhealthy for me, had my appendix been removed (which is not uncommon), given the explanation above. However, the reason I started fasting was not religious or weight motivated - I simply had no appetite. So I didn't eat. The appetite came back 21 days later. I have since fasted several times in periods of 7-21 days, once every couple of years, sometimes prompted by loss of appetite, and sometimes by wanting to experience the health benefits. I would not be surprised if appendix removal would have triggered appetite much earlier. And I would also not be surprised if evolution did not prepare humans for a removed appendix, and I would have suffered some irreversible damage as a result. I really don't know about that. (If you feel vindicated about this being "stupid and dangerous" - we have a difference of philosophy here, that I'm not going to argue about) * edit: Forgot to mention - I've been vegetarian for the most recent 90% of my life, and vegan for a nontrivial part of that - during which I never had a good source of B12. If B12 could only be sourced from food intake, I'd be dead before the age of 12 (which is why I already knew 15 years ago that the prevailing B12 theories were bullshit, despite not having a better explanation at the time). But I was only dangerously low for a 6-month period in my twenties - other than that, I was just "low, but not dangerously so" until that fast.

beagle3 14y ago

> I'm not sure what you mean by an "instance" I defined it earlier: specific person, at a specific fasting period (by which I meant contiguous period). > also depends on what you're eating during the fast. I don't think we're talking about the same thing. "fast" says "what you're eating" is nothing.

anthonyb 14y ago
Eating nothing for three weeks?! That's stupid and dangerous. You're putting your life at risk from heart attack and kidney and liver failure (and other people's, judging from your comments in this thread).
- beagle3 14y ago
  > Eating nothing for three weeks?! That's stupid and dangerous. To quote other people on this thread - "citation needed". I've done this more than once, actually, and I know others who do too. Yes, I have eaten essentially nothing for three weeks. No, I wasn't putting my life at risk of anything, though you may believe what you want -- did you notice that I'm not the only one who posted about long fasts? You just assumed everyone was eating, but we use "fast" literally, not as a codeword for "calorie restriction". Although I had the references to support that it's healthy, I did do bloodwork a couple of times through, and at the end, it was -- in fact -- much, much improved. For example, my B12 levels went from -2 sigma to +2 sigma. (If this sounds impossible to you, read the wikipedia entry about B12 - the general "knowledge", even among doctors, about B12 is unbelievably incorrect). My doctor, who is a reasonably open minded MD, looked at the results and said "just make sure you start eating when you are feeling hungry". That happened 21 days after I started. He wasn't worried after looking at my bloodwork. If you're healthy at the beginning, irreversible damage starts around day 40 (but is very swift at that point). There are quite a few people in India who do 30 days every year for religious reasons, and suffer no ill effects -- and have been doing this for centuries.
  - anthonyb 14y ago
    Your b12 will be up because your body is cannibalising its tissues to stay alive. That's your liver, kidneys, etc. and it doesn't mean that you're healthier. Given that you don't know that, and earlier on you didn't know what ketosis is, I'll take your dietary advice with a large grain of salt...
    - beagle3 14y ago
      Wow. I mean, you have all the answers! I did know what ketosis is. But ketosis DOES NOT induce acetone breath in 99.9% of the population*time - which is what I understood you asserted. Look it up. Really, look it up. And you better read about b12. You are radically misinformed. Not that I care - it's your health that will suffer. Really. Look it up.
      - anthonyb 14y ago
        No, you go look it up: http://en.wikipedia.org/wiki/Vitamin_B12#Foods http://en.wikipedia.org/wiki/Vitamin_B12#Foods. What's the top source of B12 on that list? Now, given that you're not eating beef liver, which liver do you think is providing all that B12? Stupid. Dangerous. Edit: Thinking about it, I'd put fasting for 3 weeks in the same class as running a marathon: if you can do it, you're probably healthy. Actually doing it though, is not healthy at all.
        beagle3 14y ago
        No, you read the article you quoted: Under "Foods", the section you linked: ... Ultimately, animals must obtain vitamin B12 directly or indirectly from bacteria, and these bacteria may inhabit a section of the gut which is distal to the section where B12 is absorbed. Under "synthesis and industrial production": .... Neither plants nor animals are independently capable of constructing vitamin B12.[30] Only bacteria and archaea[31] have the enzymes required for its synthesis. And a little later: .... The total world production of vitamin B12, by four companies (the French Sanofi-Aventis and three Chinese companies) is said to have been 35 tonnes in 2008.[40] Most of this production is used as an additive to animal feed.[41][citation needed] It doesn't matter what the top source on the list is if you can have it synthesized in your own body. Which I now do way better than I could before my first fast. You know why cow liver has B12? Because cows are fed B12 these days so that beef liver would have enough B12 for human consumption! That's so ridiculous and inefficient it is sad. You know why B12 synthesis is so horrible among both humans and livestock today? Because of how much we use antibiotics. And there's also another surprising finding: The human body (and most other mammals as well) have a cache of the organisms required to synthesize B12 and a host of other useful stuff. It's called "The appendix", you might have heard about it. The body will release these organisms from its cache under ketosis lasting more than a few days, to replenish and revive the useful colonies. Nature is very smart like that -- a few days of fasting are completely normal when your food source dries up. So the body uses that period to do maintenance. [I'm not going to spend time looking for the refs right now, partly because I no longer have access to full article texts, and mostly because I don't have the time; But this was hypothesized decades ago, and AFAIK conclusively proved something like 5 years ago, although it's not really well known so far even among professionals who should know better] > Stupid. Dangerous. Religious, is all I can say about your responses. You know things to be right, like it is dangerous to fast, or (I assume, although you might already be enlightened about these subjects) that dietary cholesterol is bad for you (it's almost independent of blood cholesterol, which is an important marker, though not a cause for disease), that you shouldn't eat more than a few eggs a week (nonsense; eat as many as you want - 20 a day is not unhealthy), that low-fat dietary intake is good for you (it's not), that butter is bad for you (it's excellent for you if it's from healthy grass-fed cows), that weight change is exclusively a result of caloric balance (only in the useless tautological sense), that you should minimize salt intake (too little is as bad as or worse than too much), or that cushioning is good for your feet and that's why sports shoes have them (they're bad for you except for very specific circumstances; they were championed by marketers, not researchers). I try to challenge my beliefs and understand why I have them. I often (way too often, unfortunately) find that things everyone (including myself) takes for granted are actually better classified as "wrong leaps of faith" or even downright superstitions than science. When someone contradicts me (and it's something I haven't researched and do not have a good basis for my beliefs), I try to start again from a blank slate, rather than find support for what I believe in (because you always can do that, regardless of how wrong you are). > Edit: Thinking about it, I'd put fasting for 3 weeks in the same class as running a marathon: if you can do it, you're probably healthy. Actually doing it though, is not healthy at all. I don't think this analogy is proper. Evolution surely did prepare you to run short distances. Evolution did not prepare you to run a marathon - you have to practice to be able to do that, regardless of how healthy you are - and I agree it is probably not healthy (although I have no support for that - for all I know, done properly, it might be super healthy). Evolution did prepare you to survive if your food source dries up (at least for a short while), or if you sprained your ankle and can't chase your prey or climb the tree to get food. In fact, it's apparently piggybacked some maintenance jobs on this period because (at least pre- agriculture) they were guaranteed to happen relatively often. You may argue about how long that "short period" is - evidence collected mostly from religious fasting is that it is around 40 days when you are healthy. > if you can do it, you're probably healthy. I disagree in general, but there's an important point here that I must stress - it would probably have been unhealthy for me, had my appendix been removed (which is not uncommon), given the explanation above. However, the reason I started fasting was not religious or weight motivated - I simply had no appetite. So I didn't eat. The appetite came back 21 days later. I have since fasted several times in periods of 7-21 days, once every couple of years, sometimes prompted by loss of appetite, and sometimes by wanting to experience the health benefits. I would not be surprised if appendix removal would have triggered appetite much earlier. And I would also not be surprised if evolution did not prepare humans for a removed appendix, and I would have suffered some irreversible damage as a result. I really don't know about that. (If you feel vindicated about this being "stupid and dangerous" - we have a difference of philosophy here, that I'm not going to argue about) * edit: Forgot to mention - I've been vegetarian for the most recent 90% of my life, and vegan for a nontrivial part of that - during which I never had a good source of B12. If B12 could only be sourced from food intake, I'd be dead before the age of 12 (which is why I already knew 15 years ago that the prevailing B12 theories were bullshit, despite not having a better explanation at the time). But I was only dangerously low for a 6-month period in my twenties - other than that, I was just "low, but not dangerously so" until that fast.