Glycogen Stores

Glaucus

Glaucus

Glaucus

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Wondering if anyone be kind enough to explain glycogen stores to me.

Now as I understand it average person stores about 2000 calories and that when your body runs out you hit the wall.
I'm eating low carb 75g a day on average, would I still have a full store? Or would I have even less.
Doing long distance walking up to 29miles in about 11hrs of constant walking. Mainly cross fields. Last week it was apparent 5800ft of total ascent, how accurate thi is I have no idea. Also apparently just over 5000calories, again how accurate I have no idea.
As I understand it once glycogen runs out, you start canobolising muscle to create glycogen? How does your mody decided when to burn fat/muscle.

Or am I completely and utterly wrong on everything.
 
You'll burn nowhere near 5000 calories walking 29 miles. You don't burn that many running a marathon :D

So your glycogen replenishes itself at a certain rate and you have enough sat in there to exercise vigorously (run, cycle, swim) for about an hour to an hour and a half before you've depleted it. When you're doing endurance events you take on sugar or gels in advance at intervals so that it works its way into your system to use as energy. If you don't take on sugars at intervals you do indeed hit a wall and you just crash out of energy and it's very hard to continue. Just my experience, but when you're regularly working near this exercise region, you tend to burn through body fat, not muscle.

I don't think you'll hit a wall if you're walking because you're not exercising vigorously enough to run it down like you do if you're running or cycling. You'll also be eating a meal at some point if you're out for 11 hours so you'll top it back up. That said, you will get tired on that distance and sugary things like jelly babies or Kendall Mint Cake (simple carbohydrate-rich) can be a massive boost both psychologically and in energy.

I would expect you do have a full store, but if you do this kind of exercise regularly you will have to increase the amount of carbs in your diet. You'll know when you're not getting enough - you'll just have no energy :D
 
Glaucus said:
As I understand it once glycogen runs out, you start canobolising muscle to create glycogen? How does your mody decided when to burn fat/muscle.
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When Glycogen runs out the body switches to Ketosis ie fatty acid metabolism. There is no way the body will 'burn' muscle in a fit individual unless they are in starvation at which point the body will not let you do anything remotely like running or walking at a fast pace.

A lot of it is down to fitness and getting the body used to using all the ways necessary to generate fuel.

From what I understand from Biochemistry from 20 years ago...

The fuel supply is ATP which gets generated either aerobically or anaerobically. The aerobic path uses mainly the Krebs cycle to generate ATP of which glucose is the sole energy supply. Glycogen stores at full capacity is around 3000 cal (i believe) at which point that expires fat stores begin to be utilised using Ketosis to convert fatty acids to glucose with a small amount of protein breakdown.

So a lot of it comes down to fitness and body prepared-ness, if you hardly ever go into Ketosis then it will really really REALLY hurt when you need to use it.

In short...

Glycogen ---> Glucose ---> ATP when that runs out.
Fatty acids ---> Glucose ---> ATP. I believe fat is about 10 times energy rich than Glycogen. When that runs out.
Protein ---> Glucose ---> ATP after that you are dead.


With something like cycling and long distance events its why it is so important to keep the stomach digesting sugars to keep the glycogen stores topped up otherwise you bonk i.e go into Ketosis. And the fitter the person is the less fat they will have so go straight into Amino Acid breakdown, have a monumental bonk, and the body will refuse to even move.

Also remember a very fit person will be far more efficient at using ATP molecule for molecule than someone who sits on a couch all day.

My brain hurts now so i'm off to bed.
 
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Jonny69 said:
You'll burn nowhere near 5000 calories walking 29 miles. You don't burn that many running a marathon :D
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What makes you so sure? Depending on a number of variables (e.g. body weight, amount of incline etc), it might be possible to burn something right around that figure with 11 hours worth of brisk walking. So "nowhere near" is a bit of a sweeping verdict.

As for glycogen depletion, OP is consuming less than 75g carbs per day. OP, if this is your general dieting status, then no, of course you wouldn't have a "full glycogen store". Actually you'd be pretty depleted after even a week's worth of that kind of dieting. That's a ketogenic level of carb consumption.

Most important thing for avoiding muscle loss, if this is a concern, is that you maintain your current muscle mass with suitable exercise (read: weight training) and that you have adequate protein levels in your diet.
 
Glaucus said:
Wondering if anyone be kind enough to explain glycogen stores to me.

Now as I understand it average person stores about 2000 calories and that when your body runs out you hit the wall.
I'm eating low carb 75g a day on average, would I still have a full store? Or would I have even less.
Doing long distance walking up to 29miles in about 11hrs of constant walking. Mainly cross fields. Last week it was apparent 5800ft of total ascent, how accurate thi is I have no idea. Also apparently just over 5000calories, again how accurate I have no idea.
As I understand it once glycogen runs out, you start canobolising muscle to create glycogen? How does your mody decided when to burn fat/muscle.

Or am I completely and utterly wrong on everything.
Click to expand...

I think a lot depends on how fat adapted you are, if you've been low carb for a while then your body is probably already very efficient at utilising fat for fuel, so aslong as you're consuming plenty of dietry fat then IMO you can walk 29 miles using fat/ketones as primary fuel.

This is a good article on carb requirements or otherwise during exercise.

I've gone very long periods myself (years) at sub 50 g of carbs a day but continued to train with weights and run 10k + distances on a regular basis, initially it was hard but the longer I stayed low carb the better my body seemed to become at utilising its alternative pathways for glucose/glycogen production/replenishment.

What's ideal though is open for debate, I've recently added carbs back in, in the form of starches, plantains, rice, lots of dairy, berries etc. I still have low carb days but I've found cycling carbs in on a regular basis has helped me feel and train better. Unless you have some sort of health problem, eg diabetes or epilepsy then there's no good reason IMO to be constantly in ketosis.
 
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On a keto diet, the primary fuel will be fat rather than glucose (in general, one would hope!). So theoretically the benefit of fat over glucose is it is a denser form of energy. i.e. it gives more ATP, as such more energy g for g than glucose. Also we have to add the oxygen part of this balance. Since fat is more energy efficient, it will also be more oxygen efficient, since more energy is produced per unit of oxygen.

That all seems pretty simple fat pwns! But... it's unfortunately complicated by the issue of availability, ie having the nutrients available in the right state to be used. In a high carb diet, glycogen is stored in the muscles as we all know, and provides fuel and it's delivery very quickly during intensive exercise. A keto diet quickly depletes glycogen stores. As such once your body has adapted to that sort of diet, your body is likely to have little to no muscular glycogen available to use as fuel.

However, as a result, you'll have significantly more intramuscular triglycerides to replace it. And these are readily available as fuel.

People who train regularly or in an advanced state of training, or basically atheletes in general *should* be able to metabolise (or technically oxidise) those fat stores better than people who don't train. So over time and before after diet changes you'd get different results, but it also depends on the person's level of fitness.

When oxygen can't be delivered to the cells in your muscles quickly enough to cope with demand (ie after you've been sprinting for a while) obviously it's differen person to person, an anaerobic reaction takes over where fuel burns without oxygen. If that fuel happens to be glucose, your cells will use lactic acid to extract energy from the fuel without benefiting from oxygen. As such you get that famous buildup of lactic acid in your muscles. This build up is a major contributor to fatigue and that familiar burning especially when doing HIIT.

So what happens when your body is using fat as energy instead of glucose? And when you run out of oxygen? You die! Lol! No I don't know there doesn't seem to a conclusive answers that I can work out. :) some creatine pathway is used but it's beyond me. Obviously people training on low carbs don't keel over from a form of muscle failure. That much I know. There is an anaerobic alternative to metabolising fatty acids but I don't know enough about it to explain. Also I'm on my phone without the ability to look it up.

With regards to high intensity exercise it seems thar the research is scarce and also seemingly flawed or conflicting on the factor of anaerobic lipid metabolism

I've said this before, but carbs are still relatively new to human diets as being a major macro.

Before mass agriculture, most humans probably pent most of their lives in ketosis. Typically eating meals where they had to hunt and as such undoubtedly involved loads of sprinting. It would make sense then, that we are rather adept at running while in ketosis.

I'm not going to say that even after a period of adaptation carb fueled runners aren't worse than non carb runners. However people shouldn't worry so much. However chopping and changing diets will not help your body adapt.

I'm on my phone at a car boot sale so probably cocked some things up! By not reading the replies properly apologies.
 
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Thanks.
Other than about 8 or so weekends on the sauce, where they are beer and takeaway fuelled. Been on ~75g a day since jan.

So would you suggest I eat more carbs on such days, or just stick to low carb, in which case is there a preferred fat source.
And when I say I walk for that long, I literally walk for that long, no stops for food etc. the last 29mile walk, I stopped to get seeds out my shoes twice and stopped for 5mins halfway to get some dried bananas down me and some electrolyte drink. Other than that it's just constant walking.
I do try and pick hilly routes, but it's not always possible.
 
It's not really about how much fat or carbs you eat, you just need to make sure you've got enough fuel on board to get through, 29 miles is a bloody long walk so make sure you eat higher calorie for the day or 2 before hand. I'd eat plenty of starches from potatoes, sweet potatoes, rice etc to ensure at least partial glycogen replenishment as you've been low carb for so long, aswell as loads of good saturated fats from butter, cheese, coconut oil and protein from meat, fish, eggs etc.

The body is never burning just one fuel, we're constantly switching between fats and glucose for different energy requirements. Even in deep ketosis the body will be converting fats to glucose for tissues that can only utilise glucose (kidneys for instance) & vice versa a lot of carbs/glucose will be converted to fatty acids. Good simple whole foods is all you need, the macro ratio is up to you as your body can produce required energy from high fat or high carb or a combination of both.

To carry as fodder for the day I'd say Coconut oil and bananas would be good choices as they can both produce fast energy if you find you're really flagging, aslong as you stay hydrated you shouldn't have any problems, just hope it isn't as hot on the day as it is today. A simple but effective electrolyte drink is a teaspoon of sea salt in a litre or 2 of water with a squeeze of fresh lemon juice.
 
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Freefaller said:
Before mass agriculture, most humans probably spent most of their lives in ketosis.
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I love ya and all, but this is nonsense! Reaching the small quantity of carbohydrates that would effectively avoid ketosis is easily achievable even on so-called "primal" foods. A trivial, insignificant quantity of starchy fruit or veg would do the trick just fine (and legumes, etc). Only a little over 100g of carbs would suffice to avoid ketosis (and most can probably avoid it on less). 400 calories. Hardly pushing any back-loading boundaries.

And on that note, as plants were always generally more available and easier to collect than animal stuffs, it is also nonsense that carbs are relatively new as a major macro. On the contrary, some cultures would have placed an extremely heavy reliance on plant sources of calories.

So no, real ketosis has little if anything to do with our ancestral state. And Freefaller, I know that you have carbs around training, you've said so in the past. I really recommend that you actually try to train over a period of weeks in full ketosis. Doing a strict, less than 75g worth of carbohydrates per day and not a gram more. And then report back on your sprints and heavy weightlifting performance.
 
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I have done in the past. No problem at all. :)

As I said, modern athletes with modern nutrition can achieve more unless you missed that. However, it's absolutely not necessary in my experience and opinion or scientifically. :)

I'm not saying that carbs do not help, but it really does depend on your level of training and how you use the carbs.

My point on modern agriculture is owing to the propensity of carb rich (and poor carb choices) diets over carb scarce diets.

However the OP knows now how glycogen stores work and he can make up his own mind as to what suits his lifestyle and training. :)
 
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Carbs are not the enemy and I'm not pushing an anti carb agenda. Poor quality highly processed and refined carbs on the other hand. ....
 
Freefaller said:
I have done in the past. No problem at all. :)

As I said, modern athletes with modern nutrition can achieve more unless you missed that. However, it's absolutely not necessary in my experience and opinion or scientifically. :)

I'm not saying that carbs do not help, but it really does depend on your level of training and how you use the carbs.
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But the question is essentially one of optimal performance, right? You have done it in the past and say you had no problems, but yet you now opt for a training approach that includes carbs (I think you said you teeter around 100-150g per day or something). There surely must be a reason for this choice.

I know and appreciate the point that you're not pushing a low carb agenda and stuff, but when you speak of our ancestors habitually functioning in ketosis, it really does scream of that sort of agenda. And more to the point, it's just untrue. It only takes a trivial quantity of starches and sugars to avoid ketosis. And typically, in most climates these are readily available.
 
We'll have to agree to disagree on the anthropological reasoning. :) and I'm certainly not pushing an agenda, I'm drawing examples to help highlight a point.

Yes my fruit and vegetable carb is around 100g a day, and as you say keeps me out of a ketogenic state which besides I'm not after. When I was training in true ketosis, which I maintained for several months, my performance did not decrease and I also found it easier to lose a little of the stubborn fat owing to the .calorie deficit I was undoubtedly under but also the hormonal/physiological changes my body had gone through.

Why am I back up to 100g-ish? Because I'm lazy and it's too much effort for me and my lifestyle, furthermore, and I enjoy tea/coffee with milk, and I love my fruits, and I like my food and sometimes I want to indulge in something different.

My training is no better or worse, but also through laziness I find the recovery easier, as carb and protein together helps the protein synthesis increase etc... My training regimen is so gruelling at the moment too, that just to get the calories in, without having to spend over £100 a week on food it, and have to cook for 2 people and cover breakfast lunch and dinner, is not feasible as I will not buy low quality foods.

So yes, carbs are beneficial (I never said otherwise) but they're also not as important as people make out is my point. If your lifestyle can manage without them then fine, if it's too impractical or simply not possible then don't. Eat what you feel you need, just be aware of what you're eating and how it affects your body. :)
 
Freefaller said:
So yes, carbs are beneficial (I never said otherwise) but they're also not as important as people make out is my point. If your lifestyle can manage without them then fine, if it's too impractical or simply not possible then don't. Eat what you feel you need, just be aware of what you're eating and how it affects your body. :)
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Fair enough. As I've also said before, I'm not anti low-carb lifestyles (low carb here meaning ketogenic). I just don't like it when folks put it forward as the ideal human state.
 
There is no ideal human state as even many 10s of thousands of years ago all our cultural differences and geographical placements meant we had to adapt to what we could grow, hunt, however our bodies generally react to certain nutrients the Same way, depending on how they've been conditioned. :)
 
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