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Let me introduce myself. My name is Mark Sisson. I’m 63 years young. I live and work in Malibu, California. In a past life I was a professional marathoner and triathlete. Now my life goal is to help 100 million people get healthy. I started this blog in 2006 to empower people to take full responsibility for their own health and enjoyment of life by investigating, discussing, and critically rethinking everything we’ve assumed to be true about health and wellness...

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October 20, 2008

Dear Mark: Glycogen

By Mark Sisson
107 Comments

Dear Mark,

I’m trying to understand how glucose that’s created by proteins and fats is used and stored. Is that ~200g of glycogen stored in the muscles to be used for exercise, or is it stored in the liver and used to fuel the brain and “day-to-day” functions? Also, if muscle glycogen is depleted, will ingested carbohydrates be used first to replenish muscle glycogen and then to fuel other daily functions, or are they used the other way around? I’d like to be able to use ketones to fuel my daily activity, but still have enough muscle glycogen stores to fuel intense exercise.

I always appreciate comments and questions that spur more explanation and discussion about the body’s functioning. Let’s take this one apart and have a look. Fat is always the best fuel to use at low levels of effort. We evolved to be very efficient fat-burners and even those of us at single-digit body fat levels have plenty to spare. Glycogen, as you remember, is stored glucose and is the body’s first-line energy stockpile of fuel for harder physical efforts and keeping specific systems (brain, red blood cells, kidney cells) running efficiently all day. It’s stored primarily in the liver and muscles; however, (of the two) only the glycogen stores of the liver can be used by the rest of the body. The muscles can’t share their stores. Selfish, you might say, but that’s how it works. As you suspect, the glycogen stored in the muscles (provided you aren’t taking in other glucose) is used along with fats to fuel physical activity throughout the day like your work out, your daily walk to the train, walk to the fridge, etc. The glycogen in the liver, while it can contribute circulating glucose to working muscles, generally serves up energy (reconverted glucose) to other parts of the body – the brain for example – as it sees fit.

As to the question of whether ingested carbs will go first to the muscles or to other functioning, it depends on lifestyle and how much you rely on carbs. If you are training hard every day and depending on a high-carb diet, the muscles will probably do a better job of storing those first incoming carbs from a meal eaten right after the workout. On the other hand, in the case of a low-carb strategy, the 200 grams a day you refer to are made in the liver via gluconeogenesis and mostly stored there to provide energy for vital functions. Yes, some will go to muscles recovering from a Primal-style brief-but-intense effort, but the rest stays in the liver and provides glycogen/glucose for the brain and red blood cells, etc.

Ultimately, though, this line caught my eye the most: I’d like to be able to use ketones to fuel my daily activity, but still have enough muscle glycogen stores to fuel intense exercise. I’d suggest looking at this kind of goal from a different angle. You really can’t have it both ways. Because you can’t override your body organs’ pecking order, it becomes a choice of either doing a ketogenic diet, which puts all your systems on an alternative fuel burning plan, or doing a moderately low carb diet that provides just enough glucose for your brain’s needs and for intense exercise bouts of an hour or less (centerpieces of the Primal Blueprint). If you’re looking to lose weight (fat), the ketogenic diet will be the most dramatically and swiftly successful. If you’re happy with the weight or are OK with a more gradual move toward your “ideal” body composition, the moderate-low path may be the way to go.

Finally, if it’s a question of fueling longer aerobic workouts (long distance running, for example), I’d suggest what I’ve said in the past. Endurance athletes, while they don’t need to indulge in the worst of the traditional carb loading, will need to make compromises to the Primal style. If they are “classically trained” in doing long workouts at 75-90% VO2 max, their bodies will simply require more glucose (and, hence, muscle glycogen) to accomplish the feats asked of them. In that case, ketones can’t play much of a role. On the other hand, it is possible – over a long period of time – to redirect gene expression to favor fat and ketone metabolism even at higher workloads. But this requires that the training be done at much lower heart rates for longer periods of time. That becomes the only way to recommend endurance athletes adapt their training and diet regimens to maximize fat burning efficiency. Check out Primal Compromises for Athletes for more on that discussion.

As always, thanks for your questions and keep ‘em coming!

Bob.Fornal Flickr Photo (CC)

Further Reading:

The Definitive Guide to the Primal Eating Plan

What Happens to Your Body When… You CARB BINGE?

The Context of Calories – 200 Calories is 200 Calories. Right?

Dear Mark: Did Our Bodies Evolve to Run on Ketones?

The Entire Definitive Guide Series

TAGS:  ketosis

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107 Comments on "Dear Mark: Glycogen"

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Mike OD - IF Life
7 years 11 months ago
Good read. As I like to tell people, eat enough carbs just to keep you awake and muscles fueled for explosive work that day and then use fat to burn all day long. Best time to reload is of course after muscle glycogen depletion exercise (more resistance training, not endurance) when they are more primed for intake (which of course is not every day too). Meat+Fat+Veggies most the time…..Meat+Carbs postworkout recovery as needed. Of course if fat loss is the goal one must be careful of carb levels pwo, as too much will just create a spillover effect and store… Read more »
Bud
Bud
7 years 11 months ago

I always thought the ketogenic diet worked on a gradual sliding scale rather than an either/or. So then the question becomes, at what point does the body make the switch from burning carbs to ketones? I’m assuming it’s different for every body, but would the number typically be under 100 carbs/day or under 20 carbs/day?

Alex
Alex
7 years 11 months ago

Great information. Thanks. I also echo Bud’s question – although, as he does, I suspect it’s different for everyone!

Holly
Holly
7 years 11 months ago

The classic ketogenic diet, from my understanding, is comprised of 88% fat, 10% proteins and 2% carbohydrates. So the exact number does depend on how many calories one consumes.

Tee
Tee
7 years 11 months ago

Interesting topic. What would you recommend for someone who has big weight to lose? This person is 47-49 YO, male, and has at least 150 lbs. to lose. I would like to help him reach his goal. Any info pertaining to this subject would be greatly appreciated. My key questions are how many cals per day, protien, fat, and card brake down, and how long can one stay on the ketogenic diet
Thank you.

Aaron
7 years 11 months ago
Tee – Read this: http://www.marksdailyapple.com/definitive-guide-to-the-primal-eating-plan/ It is a good starting point. Also, the Primal Health Challenge Series could stand as inspiration: http://www.marksdailyapple.com/30-day-primal-health-challenge-final-results/ To lose weight quickly cut carbs over time until you get down to approximately <50 g of carbs/day. Maintain this level of carb intake while losing weight and then slowly ramp up to between 100-150 g carbs/day for the long term. Truth be told most anyone that is overweight is going to lose weight by eating the right foods and keeping carb intake to that 100-150 g/day level. Cutting them further will just make the weight come off… Read more »
Mark Sisson
Mark Sisson
7 years 11 months ago
Bud, you are correct that the body works on a sliding scale here. We are always making some ketones, but that is very little when we have a high carb diet. As we lower carbs, we ramp up the ketone contribution a little…but fatty acids are still providing the bulk of energy. The problem in the question above has to do with exercise. When we exercise at high intensities, we generally call upon the glucose machinery to fuel the efforts. Then we feel the need to replace the glucose with a ton of carbs. That cycle just keeps repeating and… Read more »
Bud
Bud
7 years 11 months ago

Indeed it makes sense! Very well explained, never really understood ketones until today.

JE Gonzalez
7 years 11 months ago

Just wondering if you could consider a diet with 60-80 grams of carbs but 30 grams of fiber ketogenic since the net carbs will be a bout 30-50?

Mark Sisson
Mark Sisson
7 years 11 months ago

JE, that would certainly be ketogenic provided your protein is at less than 150 grams a day (since excess protein converts to glucose).

Son of Grok
Son of Grok
7 years 11 months ago

This post made me go back and count how many carbs I am getting in a day because honestly I haven’t been calorie counting because all I usually eat is good food. I was worried after reading this because I usually have 1/2 a grapefruit and either an apple or banana every day so I thought maybe I had too much fruit. By my calculations, even with all the fruit and veggies, I am still in the 100-150g (closer to right around 100) of carbs per day range which is refreshing!

Mark Sisson
Mark Sisson
7 years 11 months ago

Son, most people who cut all grains, simple sugars, desserts, potatoes, etc and just rely on veggies and fruit still fall below the 150 grams/a day line, eveb if they have fairly ample servings of those…so it’s a whole lot easier to be Primal than most skeptics think.

Fixed Gear
7 years 3 months ago
Absolutely! Since going primal, I don’t count carbs or calories at all. I just try to eat primal foods. I eat as much as I want. In the 13 weeks I’ve been doing this, I’ve dropped 13 pounds. ….really without trying. The only effort is avoiding high carb foods in our world. And they are tasty. But if you’re FULL on good primal foods it’s not that hard. I can say no to a burrito with a white flour tortilla, beans and rice, because I just had a steak and broccoli dinner. 🙂
Ryan
7 years 11 months ago

I have never counted calories, or grams of carbs. I have found that on a near PB diet, I simply eat what I feel I should eat (Veg, fruit, protein, fat, and/or tubers), based on how my body feels. Going by feel is one of the best things about the PB diet – your body tells you what you want!

Grounded Fitness
7 years 11 months ago

I was eating a banana when i pulled up your site. and then i looked at it and it was the same sticker.

get out of my house, mark.

Kelly Turner
http://www.groundedfitness.com

Mark Sisson
Mark Sisson
7 years 11 months ago

Kelly, didn’t mean to spook you. Guess you were meant to read that post!

Andrew R
7 years 11 months ago

When you talk about how you can’t have it both ways in relation to “ketones to fuel my daily activity…” and “muscle glycogen stores to fuel intense exercise”, is that the answer to why you can’t burn fat and build muscle at the same time?

Thanks for the post!

All the Best,

Andrew R

Mark Sisson
Mark Sisson
7 years 11 months ago

Andrew, you actually can build muscle and burn fat at the same time – just not so easily while you are focused on a ketone-based metabolism. Under normal low carb (high fat and moderate protein) circumstances you can easily build muscle working out and still burn fats. Remember, you don’t have to be in ketosis to burn off stored fat. That happens anyway when you cut carbs and keep calories reasonable. It just happens a bit quicker when you decide to cut total calories AND keep carbs low enough to promote ketosis.

trackback
7 years 11 months ago

[…] my eyes rolled out of my head), I was told there would be pie, Mark does “D“, glycogen redux, a lab in every kitchen, what’s really in your food, be careful nuking that chicken, you are […]

ebrunner
ebrunner
7 years 10 months ago
I’m trying to transition to a “semi” PB lifestyle since I’m currently doing too much running, which just seems to beat me up. Still, I enjoy running and working out, so I do want to be able to do a decent amount. Here’s the schedule I’ve been following: M: 2 miles slow jog to the track, 12×400 w/200m jogs, 2 miles slow jog back. T: Weights: 4 sets each for chest, back, shoulders, biceps, triceps, legs (either squats or deadlifts). 45 minutes slow jogging total (2 mile jog to gym and a 4 mile loop home) W: 2 miles slow… Read more »
gary d
7 years 10 months ago
I have been following a low carb diet since the onset of my running addiction (lol), about 1.5 years now, but I do mostly run under 60 minutes at a time, and focus more on speed than marathon type endurance. I slow down quite a bit as distance increases, but I don’t know if that’s due to my diet or simply cos I haven’t been running that long yet. I broke 20 minutes in my first 5k, and I’m almost 40, so yes you can perform quite well on low carb. I have found that if I take carbs on… Read more »
gary d
7 years 10 months ago
sorry, forgot to add, for the “ebrunner” question…I run intervals twice a week, 200’s and 400’s, at a fast (for me) pace, about 5.30/mile pace or so. The “key” that will open your muscles to high-speed work is sugar, that is my experience. Take it like I said, before/during/after, I take about 75-125g of sugar total depending on how I feel… then I put it away and go back to low carb. I can’t go fast without the sugar myself, and I’ve been low carb for 4 years! The recipe for my drink is on my blog page.
ebrunner
ebrunner
7 years 10 months ago
Thanks Gary. What do people think about reloading with fruit (especially bananas)? One could still be eating mostly PB-style, just with a higher carb intake. About how any carbohydrates are needed to fuel a hard interval workout (i.e., 12×400 w/200m jogs)? That’s ~3 miles hard (I’m assuming 100% carb-fueled); I figure 100 calories/mile, so 300 calories, or 75g beyond what I would eat on a slow day? Or can some of this glycogen replaced by converting lactate back to glycogen, or from gluconeogenisis, etc? All told, the workout ends up being 8-9 miles, with warmup, cooldown, recovery jogs; but I’m… Read more »
Mark Sisson
Mark Sisson
7 years 10 months ago
ebrunner, the hard interval workout in and of itself can be done on just the glycogen stored from the prior 24 hours even on a low-carb program. The issue is whether the interval is done on a day after or among several other days of running medium-to-high pace. Then you can’t be expected to refill glycogen that quickly, That’s why the PB system says do low level (walk, hike, easy ride) stuff that burns mostly fats…then once a week do intervals. That one workout might require 200 grams of glycogen, but it’s all there. Then, as long as you don’t… Read more »
ebrunner
ebrunner
7 years 9 months ago
Makes sense, thanks. So, under a low-carb program, total volume of intense training has to be limited, and “easy days” have to be very easy in order to recover. Which begs another question: if under a low-carb program, would it be better (for the purposes of fat burning/body composition, not athletic performance ) to do the 12×400 type workout once every three days, or do 4×400 every day? Total volume of intense running is the same in either scenario. My guess is that the daily workout would be more effective because one is creating the post-workout environment every day (GH… Read more »
Mark Sisson
Mark Sisson
7 years 9 months ago

ebrunner, 4 x 400 every day gets you nothing in terms of adaptation. 12 x 400 once a week might. Even 12 x 400 every three days is too much (if you are doing it right)

ebrunner
ebrunner
7 years 9 months ago
Mark, I’m talking purely for fat-burning and hormone response purposes, not for exercise performance. I realize the 4×400 every day is useless for a distance runner looking to improve performance, but what about someone who is simply looking to keep their GH elevated as they age? I If 12 x 400s is a once/week workout, what about 6×400 twice a week? Or 10×100 every morning? I get a bit of a buzz from doing some intense running (even a small amount) that fires me up for the rest of the day; I’d rather get this buzz daily vs. doing a… Read more »
Mark Sisson
Mark Sisson
7 years 9 months ago

GH requires short intense bursts. If it’s something you can do every day without getting injured after a while, it’s probably not intense enough. Running is just one part of training. You might sprint once (or at most twice) a week. then you might do a heavy leg lift day once a week. Those two or three workouts would be sufficient (and recommended) to maximize HGH output. The rest of your exercising would go toward low level aerobic acitivity, play, or “maintenance” full body work….and, of course, recovery – the most important part of training.

Kaan
Kaan
7 years 8 months ago

I am on a very Low-carb diet ie Atkins Induction phase <20g carb per day, but have 2 slices of wholegrain multi-seed bread after my 1hr swim in the morning & an apple before my dumbell workout in the evening,
I am considering a pre-w-o carb up once a week to enable me to perform a very heavy kg workout of compound weight lifting exercises to raise muscle mass in order to burn more fat.
Will coming out of ketosis slow my fat burning or would it be worth it?
All comments appriciated

Kaan

mark sisson
mark sisson
7 years 8 months ago

coming out of ketosis does slow your fat-burning somewhat, but if you are already at low body fat, it probably doesn’t matter.

Matt
7 years 8 months ago

So what do our muscles use when we are in ketosis for fast energy?

I’m eating very low carbs (below 20g/day) and doing intense but short interval training w/ weights, kettle bells and body weight 5 days a week. I’m concerned that I’m not getting enough carbs to make my exercise effective, both in terms of gaining lean mass as well as sacrificing my energy overall. Do I need to eat more carbs if I’m exercising in this way?

Mark Sisson
7 years 8 months ago

Matt, if you’re exercising less than 40 minutes a day, you won’t use that much glycogen that you can’t replenish it through gluconeogenesis

armand
armand
7 years 7 months ago
Mark, I am an avid runner and have been for many many years. Recently (about 2 weeks now) I started a ketogenic diet (very very low carb) for weightloss as well as other health benefits. I have continued running, spinning, and swimming with no problems yet that I can tell. In the past before an event (10k, tri, etc) I would take a gu pack about 30 minutes before. I am running a 10k race this weekend and am hoping for about 6:30 pace and was wondering if you think I should take the gu prior to the race or… Read more »
Ryan Denner
7 years 7 months ago

Armand,

If you have not been training with it, then don’t take it. I myself have adopted a low carb diet while training for endurance athletics with a lot of success. I say as long as you fuel properly the day BEFORE, and morning OF the race, then you will probably be fine. Although, it won’t hurt to bring it with you just in case!

Best,
Ryan

armand
armand
7 years 7 months ago

Ryan,

Thanks for the reply. I totally understand and usually stand by the don’t do it if you haven’t trained with it moto. I guess my ignorance is that I have always loaded up on the pasta, bread, and other starches that I am no longer consuming therefore don’t really know what to fuel properly with the day before without having carbohydrates and coming out of ketosis. Any ideas? Thanks so much!!

Armand

Ryan Denner
7 years 7 months ago
During the day before, try some potatoes and/or brown rice to top off the glycogen stores (no processed carb like pasta/bread). If you are worried about sugar, then have some low fiber fruit in the morning. Also, before the next time you do a 10K, do a tempo run at 10K pace for say 30 minutes, and see how your body feels. I’d definitely look at this 10K as a learning experience and see how your body deals with racing on low carb. It definitely is doable. Again, take the gel with you just in case.
armand
armand
7 years 7 months ago

thanks again Ryan. You have been a big help. I agree with you about looking at this race as learning experience. Hopefully all will go well. I guess with starting a different eating lifestyle I am just a little anxious b/c I know what I am capable of in the past and hope to do as good or better. Thanks again!!

Armand

Mark Sisson
7 years 7 months ago

Armand, I agree with Ryan. Take a gu packet with you just in case, but the truth is, a 10k in 37-38 minutes will “only” require about 200 grams of stored glycogen. You should have enough stored if you taper or take the day or two before the race easy

armand
armand
7 years 7 months ago

Thanks Mark!! Again I guess my ignorance about low carbohydrate intake and glycogen is becoming more and more evident. I was under the impression that severly reducing carbohydrate intake lead to depletion of glycogen stores requiring your body to get energy solely from fatty acids.

Mark Sisson
7 years 7 months ago
The body is always getting energy from a combination of fats, glucose/glycogen, protein and carbs. Low carb intake causes you to burn more fat, but also prompts gluconeogensis (because you still need SOME glucose). That is driven by fat metabolism and ketone formation. When you race while trained to burn fats, you still need some glycogen in the muslces. When glycogen is depleted, you hit the wall (you can still walk or jog easily, but can’t run fast). That’s why you might carry the gu….just in case. Probably won’t be a factor in a 10k, but would be more so… Read more »
armand
armand
7 years 7 months ago

Excellent!!! I really appreciate all the help. I think I understand that aspect better now. One other question I had was, lately if I really push myself on a run (3 – 5.5 miles) I notice a little more cramping in my quads than pre ketogenic diet. Do you believe this is some effect of the diet or just a failure on my part to hydrate correctly or proper electrolyte intake?

Ryan Denner
7 years 7 months ago
I am not sure if “they” have ever figured out what causes cramping. “They” used to think it was electrolyte imbalance, but the latest theory is your muscles cramp because they are not used to doing a certain motion/load. It might be either, or hydration, or a combination of some/all. Regardless, your muscles cramp b/c they can’t do what you want them to do anymore! Try keeping with your diet, *maybe* hydrating a little more, ran at this “hard” pace a little more often (do you warm up properly before running hard?), and maybe even included some stretching, you would… Read more »
armand
armand
7 years 7 months ago
Thanks Ryan. I will def try some/all of your advice. I do intend to continue the diet and hope that this effect is something that I can work through or figure out how to combat it. I know i don’t stretch ‘enough’ and probably could hydrate a little more than I do. It had never been a problem before so it never bothered me. But being on a different diet I guess can lead to different physiological experiences. I tend to do a good job of hydrating in preparation for an even and def during the event. Thanks again for… Read more »
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[…] with a price when the body will just end up storing their energy. As I mentioned a few weeks ago, glucose in the bloodstream has toxic implications unless it’s being stored or burned right away as […]

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[…] Dear Mark: Glycogen – Glycogen is stored glucose and is the body’s first-line energy stockpile for hard physical effort and other specific body functions. Learn how and where glycogen is stored and how and when it is used. […]

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[…] regimen. It’s easy to do (because every bit of movement counts) and it doesn’t dip into your glycogen reserves (making it a pure fat burner, not a sugar burner). If you’re on the low end of the […]

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[…] regimen. It’s easy to do (because every bit of movement counts) and it doesn’t dip into your glycogen reserves (making it a pure fat burner, not a sugar burner). If you’re on the low end of the […]

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[…] your efforts and repair your body, along with (only) as many added carbs as you need to replenish glycogen. In addition to providing proper fueling, eating only animals, plants, fruits, and nuts, while […]

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[…] solid fitness), but more than an hour’s time for most folks requires some extra carbs when glycogen is depleted. If you’re bothered by the mental fog even without intensive exercise, ease up on […]

Jeff
5 years 10 months ago

Great read, I always enjoy reading about the specific details of your posts Mark.

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[…] strategy that is NOT part of the PB Fitness plan, by the way) you will want to be sure to top off glycogen stores after each hard workout to prep for the next. That does mean upping your carbs from fruit or […]

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