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Thread: Intermittent Fasting - A Primer ( Part 1 ) page 2

  1. #11
    JillianMarie77's Avatar
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    Quote Originally Posted by Chloe View Post
    I want this on a T-shirt!
    Yes Please
    Jillian
    Strict Vegetarian going primal as of 3/2011. This is a tough row to hoe!

    So far I am down:
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  2. #12
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    Quote Originally Posted by marcadav View Post
    DFH, I referenced this earlier:

    "Composition of the diet rather than reduction in the total calorie intake seems to determine the occurrence of decreased T3 generation in peripheral tissues during food deprivation. The dietary content of carbohydrate appears to be the key ingredient since as little as 50 g glucose reverses toward normal the fast-induced changes in T3 and rT3.52 Refeeding of protein may partially improve the rate of T3 generation, but the protein may be acting as a source of glucose through gluconeogenesis.54 Yet, dietary glucose is not the sole agent responsible for all changes in iodothyronine metabolism associated with starvation.
    I feel that we are talking at cross purposes. You may not be expressly aware of it, but we are actually discussing hormesis here, the term for generally-favorable biological responses to low exposures to toxins and other stressors. A pollutant or toxin showing hormesis thus has the opposite effect in small doses as in large doses.

    As you can see in the graph below, for any arbitrary "stressor" or substance, there is a band where that substance is stimulatory to the organism, and pretty much harmful at lower or higher doses. This is hormesis in action. If you don't like Greek, you can think of this as the Goldilocks principle, there is a dose range that is "just right!", which I propose to call the efficient frontier:



    Before we get too lost in dry academic language here, let me put "stressor" into context. Let's consider that even one of the most fundamental constituents of our bodies, water, exhibits hormesis and an efficient frontier. We all know that without water for just a few days, we will die. Drink too much water, and you will die due to acute water intoxication. Get the right amount of water and you will thrive.

    And this is where our paths diverge. I keep trying to answer the question "What is the range for meal frequency where we can thrive?" and replies are coming back with "What happens when you push the meal frequency to the extreme right in the hormesis graph?" To answer that question, I actually don't need to reference any study, because I can just go back to the principle of hormesis for the answer. It may be a tautology, but here goes "when you leave the efficient frontier of the hormesis graph, the stressor will cause damage to the organism, perhaps catastrophically so."

    Nevertheless, there is work to do here. So, the initial quote above while interesting immediately raises some flags that I would want to investigate. I've highlighted the problematic issues in bold, and it essentially boils down to what did the authors of that original paper actually study? What is hiding behind the phrase "food deprivation?" How many calories? How often? For how many days? The fact that they refer to iodothyronine metabolism during "starvation" makes me suspect that we are looking at prolonged periods without food, much in excess of 48 - 72 hours, and more than likely beyond the efficient frontier for meal frequency. Without access to the full study, however, I cannot do anything but speculate at this point.

    This is a pretty good reference, mostly because we have access to the full text of the study, so we can determine whether it applies here, or not. It does not because it addresses the effects of fasting over 10 days, which I believe is beyond the efficient frontier and definitely into potential starvation.

    I'm not going to expressly look at this study, for lack of time, I may come back to it later. I will say, however, that it addresses an unhealthy population subsegment, those that have needed surgical intervention to address their problems. As such, I would be extremely cautious in drawing any conclusions from it if you do not belong to the same population as those under study ( ie individuals with a jejuno-ileal bypass )

    I do not see using "eating windows" or intermittent fasting being globally harmful. I do believe that intermittent fasting, for people with known rT3 issues, should be weighed carefully with input from their physician.
    +1000

    We are in violent agreement here. If you are not healthy, particularly with respect to your thyroid metabolism, see your doctor before doing things which will impact on thyroid metabolism. Fasting will impact thyroid metabolism. This is natural and expected. If fasting does not impact thyroid metabolism, that in itself is a pathological condition.

    Maybe I may have time later to look at this...

    -PK

  3. #13
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    Quote Originally Posted by DFH View Post
    It could very well be that IF, as practiced, typically does not include enough time for rT3 to elevate and become an issue. It could be. But just based on the responses I have seen in the past few days, it has raised my suspicions as far as is anyone really paying attention? I just don't see it yet. People are dismissing the question or appealing to authority ("smart people say do it so just shut up..etc"). The question could easily be closed by a single reference to a single study where rT3 was taken into account and found to not be an issue.
    PK, This was what I was responding to. I was providing references to help DFH see what happens in respect to rt3.

    If increased rT3, in connection to food deprivation and starvation "reverses toward normal the fast-induced changes in T3 and rT3" with 50 grams of glucose and/or protein refeeds, then any possible rT3 issues during IF--which is not deprivation or starvation--would be mitigated by the same pathway outlined in the quote.

    IMO, the other studies provided support rT3 improvement with refeeds following calorie restriction and/or undernutrition.

  4. #14
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    Jac
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    Quote Originally Posted by pklopp View Post
    what did the authors of that original paper actually study? What is hiding behind the phrase "food deprivation?" How many calories? How often? For how many days? The fact that they refer to iodothyronine metabolism during "starvation" makes me suspect that we are looking at prolonged periods without food, much in excess of 48 - 72 hours, and more than likely beyond the efficient frontier for meal frequency. Without access to the full study, however, I cannot do anything but speculate at this point.
    Would you like me to try and get hold of the original study? I'm not sure which one you're referring to, so if you send me the details I'll give it a try.
    Started Feb 18 2011

    Journalling here

    "There's a difference between knowing the path, and walking the path" - Morpheus

  5. #15
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    Wow - that was a fantastic post and I can't wait for part II. Coming up?

  6. #16
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    Quote Originally Posted by marcadav View Post
    PK, This was what I was responding to. I was providing references to help DFH see what happens in respect to rt3.

    If increased rT3, in connection to food deprivation and starvation "reverses toward normal the fast-induced changes in T3 and rT3" with 50 grams of glucose and/or protein refeeds, then any possible rT3 issues during IF--which is not deprivation or starvation--would be mitigated by the same pathway outlined in the quote.

    IMO, the other studies provided support rT3 improvement with refeeds following calorie restriction and/or undernutrition.
    Oh, I see ... roger that, then!

  7. #17
    pklopp's Avatar
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    Quote Originally Posted by Jac View Post
    Would you like me to try and get hold of the original study? I'm not sure which one you're referring to, so if you send me the details I'll give it a try.
    I would definitely welcome the help in tracking that study down, please!

    I'm not sure how much luck you will have, though. Here is where that came from. It looks to be an online book, and I don't know whether they actually have the data and methodology backing the conclusions. Maybe the principals behind that website might be able to dig up the data?

    -PK

  8. #18
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    excellent post. probably the most definative post covering IF i have seen. and ive read quite a few....

    looking forward to part 2

  9. #19
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    pklopp, I am really starting to get a man-crush on you. This is guest-blog-post worthy stuff. Thanks.

  10. #20
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    awesome post, thank you!

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