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What's the deal with Glycogen?

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  • What's the deal with Glycogen?

    So, Mark doesn't recommend doing carb refeeds for people trying to lose weight, like me. I did do the sweet potato thing for a couple of weeks and have since stopped since i took a break from lifting. What exactly does glycogen do and what effect does it have on building muscle?

    Also, if I don't do carb refeeds, does that mean I should continue to restrict the amount of fat that I consume on lifting days?

  • #2
    Glycogen is basically sugar stored in your liver and muscles that they can use as fuel. If you're going to be doing any kind of endurance training or some extended and intense strength training then you will want to have a supply of glycogen on hand and in your muscles. What muscles actually burn as fuel is called ATP and you can feel this getting depleted as you do your reps. The function of glycogen is to be turned into ATP and used as fuel not in actual muscle building. What you need to reconstruct and to build muscle tissue is protein, but if you don't have the fuel to do the reps then the protein isn't going to get the chance to do it's job.
    So, if you're just trying to lose weight and you're not doing any intense training then I wouldn't bother with carb refeeds. Restricting the amount of fat that you consume/vs carbs just depends on how much fuel your body needs.


    • #3
      Daemonized - great, succinct and descriptive post.

      so then does it follow that if the goal is to build strength without concern for weight loss that glycogen refueling should be introduced?

      Is eating a primal meal post-workout the same as glycogen refueling? Or should there be more simple sugars and carbs.

      Since I stopped trying to lose weight a while ago I have given up a few tenets of Primal like intermittent fasting so that I can gain more mass. I'm trying to find the places for improvement to help me grow beyond my 200lbs. perpetual plateau. It's really hard to put on mass for me eating primally.
      ad astra per aspera


      • #4
        If you're fasting or eating fairly low carb (anything close to ketosis) consistently then your body will not have a full supply of glycogen. You could eat primal food with plenty of primal carbs and keep your supplies full if you wanted. Sweet potatoes, potatoes, squash, and other veggies make good refeed foods. Sticking with lower carb primal foods will not give you enough carbs to really store up a lot of glycogen.
        Glycogen is also easily detectable on the scales because it is what is responsible for a lot of one's water weight. While glycogen in and of it's self doesn't weight all that much on a 150 pound frame you can get about five pounds into your muscles and the effect is visible all over your body.


        • #5
          I started eating lots of yams a few weeks ago and increased my vegetable intake substantially. Yams are amazing btw.

          I will experiment with non grain/refined sugar carb loading to see what happens. More fruit shipped in from across the world I guess.

          The body "bulking" as you describe with the glycogen reminds me of when I cycle creatine - it's like a cartoon character getting blow up like a balloon. I'll give it a go.
          ad astra per aspera


          • #6
            Glycogen is the brains preferred source of fuel, you need it. It is the preferred source of fuel for muscles too, but it is consumed quickly and is not a source of prolonged energy. Restoring it is pretty easy if you just eat a sensible meal within about 30 minutes of hard exercise where you tapped into the glycogen stores. When your body can't get the glycogen from your food, don't worry, your liver manufactures it for you while going about your day. You body will consume glycogen overnight so you are slightly depleted in the morning when you wake up.



            • #7
              An important note: Glucose (Glycogen) is the brains only source of fuel. It cannot use fat like other body cells, which is why hypoglycemic diabetics have an altered mental state.


              • #8
                Karma and gator: I'm not trying to be picky, but glycogen is not the same as glucose. It is the form that we store glucose in. If we could directly burn glycogen, glycogen storage diseaes wouldn't be a problem. Some people do not produce to enzymes necessary to break down glycogen and this can be a very serious health problem. Also, the brain can use ketones for most of its needs, but yes, it does require some glucose. Red blood cells also require glucose (they don't have mitochondira).


                • #9
                  yodiewan, I hear what you are saying but Ketone bodies are only used as an alternate fuel when glucose is not available, esepcially in a fasting situation when all glycogen stores have been depleted. It is in no way the primary fuel for the brain which is why when we come across diabetic patients with an altered mental status we give them glucose. Ketone is only really produced during fasting periods and is not as efficient a fuel. I'm not a doctor but that's my basic understanding.


                  • #10
                    You might want to look into something called "glycogen supercompensation".

                    Basically it involves working out in the fasted state in order to get the most out of your glycogen stores and to promote an adaptation that will allow your muscles to store more glycogen in the future.

                    By working out the in fasted state you are making sure that you are using up practically all of your muscle and liver glycogen. In fact, for a normal person their glycogen stores are pretty much depleted after about 24 hrs of normal activity so their intensity level on any kind of strenuous exercise would not be great and they would start burning fat as a primary source of energy for the workout.

                    The body would then compensate by expanding your glycogen stores (in essence it expands your "gas tank") so that you can have more energy for the next bout of fasted exercise.

                    This is what i have been doing for a while and it seems to work really good. I fast for 24 hrs then workout at around the 22-23 hr mark, my body has gotten used to this and i've got plenty of energy at this point, so that's never a concern. Then when i'm done my workout i gorge for another 24 hrs and watch my muscles soak up the carbs and water. It's pretty amazing the difference 24 hrs makes between muscles that are glycogen depleted and muscles that have just been "refueled".

                    My workouts are usually sprints and various compound exercises, these seem to be the best for improving strength and body composition.