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Thread: Glycogen is maintained and replenished during ketosis. page 7

  1. #61
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    Quote Originally Posted by Neckhammer View Post
    Well, so when you two are discussing "sport science" your just talking sports nutrition then right?

    In that light its as soft a science as any other in the biological field.
    No, I mean sport science in general, which has overlays with a number of areas of research. Sports nutrition research is absolutely just as much a biological science as any other nutrition research (although there's a behavioural science aspect to some of that stuff as well since food behaviour is relevant in an athletic context).
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  2. #62
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    I was referring to the nutrition as that was clearly what was under discussion. I've studied sports science from the perspectives of metabolism, nutrition and biomechanics.

    Biomechanics is the clearest cut IMO.
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  3. #63
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    Quote Originally Posted by paleo-bunny View Post
    I was referring to the nutrition as that was clearly what was under discussion. I've studied sports science from the perspectives of metabolism, nutrition and biomechanics.

    Biomechanics is the clearest cut IMO.
    It may be. Its definitely the area I study the most. But, neuromechanical feedback does interplay with physiology and you can get just as many competing theories at that level as any other.

  4. #64
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    Hey, but glycogen is maintained and replenished during ketosis . Back on track!

  5. #65
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    Quote Originally Posted by Neckhammer View Post
    It may be. Its definitely the area I study the most. But, neuromechanical feedback does interplay with physiology and you can get just as many competing theories at that level as any other.
    Why do you study neuromechanical feedback the most?

    I'm sure it does have complex interactions with physiology. I am genuinely interested.
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  6. #66
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    Quote Originally Posted by Neckhammer View Post
    Hey, but glycogen is maintained and replenished during ketosis . Back on track!
    Not really. The training period reduced liver glycogen by about half and muscle glycogen by about a quarter, and both were further reduced on the experimental day. The trained rats only replaced half the liver glycogen that was lost on the experimental day (one day) while replacing very little in the way of muscle glycogen.

    And this was with running. The only people who would accept this study as proof of the ability of ketogenic diets to maintain suitable glycogen status for athletes are the ones who didn't read it. Eventually the glycogen's going to run out.

  7. #67
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    Quote Originally Posted by Timthetaco View Post
    Not really. The training period reduced liver glycogen by about half and muscle glycogen by about a quarter, and both were further reduced on the experimental day. The trained rats only replaced half the liver glycogen that was lost on the experimental day (one day) while replacing very little in the way of muscle glycogen.

    And this was with running. The only people who would accept this study as proof of the ability of ketogenic diets to maintain suitable glycogen status for athletes are the ones who didn't read it. Eventually the glycogen's going to run out.
    I'm not convinced. If you're eating a reasonable amount of protein, then, even if you're in ketosis, there should still be a fair amount of gluconeogenesis. At the very least, it will be enough to fuel your activities if not absolutely stuff your muscles and liver with glucose.

    If you are more athletic, I have a feeling your body would eventually recognize this (at least, once it adapted to being in ketosis), and it would know it needs more glycogen to fuel activities. Therefore, once it figures this out, gluconeogenesis would probably be somewhat unregulated to fill the additional needs. This is not immediate of course, and the body would need to both adapt to being in ketosis AND figure out the proper dosage of glycogen needed. That makes for a significant transition period that many athletes indeed might have to struggle through with reduced glycogen stores. A lot of athletes might not have the perseverance (or indeed the ability) to make it through this transition period based on the demands it places on the body. But athletes that thrive in the ketogenic state have probably done just this.

    On the other hand, if you are on an "old-style" ketogenic diet where 80% or more of calories are coming from fat, then yeah, you might have issues. You have to get the glycogen you need somehow.

    It just seems to me that it's simply not right to assume that there's only one way (eating carbs) to do this. I will agree that it is the simplest and easiest way perhaps, but is it the most optimal or most effective? I still think that that depends on the specific individual to whom we are applying it to.

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    Quote Originally Posted by Drumroll View Post
    On the other hand, if you are on an "old-style" ketogenic diet where 80% or more of calories are coming from fat, then yeah, you might have issues. You have to get the glycogen you need somehow.

    It just seems to me that it's simply not right to assume that there's only one way (eating carbs) to do this. I will agree that it is the simplest and easiest way perhaps, but is it the most optimal or most effective? I still think that that depends on the specific individual to whom we are applying it to.
    This is actually my theory on why I felt so crappy on VLC. I know that some people talk about the "zone of misery" and suggest limiting protein, but when I look at what I was experiencing, I think it's that I was not eating enough protein for both gluconeogenesis and muscle building/repair. With the demands of frequent Crossfit and other activities, I think I was eating far too little protein for my requirements and my body couldn't keep up.

    However, I don't feel like testing it out on myself when the simple solution for me was to eat more starchy vegetables and fruit. Potatoes are much more cost effective than adding in another steak daily, and they don't cause me any issues, so I'm happier eating more carbs.
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  9. #69
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    Making such an argument for gluconeogenesis seems to run counter to the current trend of nutritional ketosis, which is all about reducing the protein. Regardless, the trained rats had higher glycogen stores through the training and replenished them better, but all the adaption in the world isn't anywhere near as effective as just eating some glucose.

    But as far as "adaptation" goes, I'd like to see a longer study like this with resistance training in humans to see just how much glycogen the body can produce in ketosis, where it goes (in the trained rats it went primarily to the liver), and how it varies among individuals. But I feel like the results would be more of the same, if not substantially worse.
    Last edited by Timthetaco; 12-12-2012 at 08:07 PM.

  10. #70
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    Owly, if you are more active, then you burn through the glycogen from gluconeogenesis pretty darn quickly. For an athlete, this allows them to stay in ketosis fairly easily on a much higher protein diet (30-35% or even 40% for the highest level athletes). This may even be a necessary adaptation to making ketosis a sustainable state for athletes.

    On the other hand, if you are someone who doesn't get much activity, in order to maintain ketosis you may HAVE to eat much less protein. Otherwise, the gluconeogenesis that is occurring from excess protein will catch up with you and bump you out of the ketogenic state.

    To sum, athletes can maintain ketosis fine, but need significantly higher protein concentrations in their diet to fuel the necessary gluconeogenesis AND they have to be able to make it through a transition period for their bodies to adapt to ketosis and up regulate gluconeogenesis. Nobody said it was going to be easy.

    Sedentary individuals (or even once a week weightlifters) may need to eat more fat, less protein so that gluconeogenesis doesn't get out of control and create glycogen that doesn't get used up, thus bumping them out of ketosis.

    What kind of ketogenic diet you choose depends in large part, what your other lifestyle factors are that may affect your outcome.

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