Questions on nutrition, carb intake, glycogen stores and fat conversion

I try to put my questions very short and simple (I’m afraid I will oversimplify a complex topic…so thanks for enlightening me).

  • Q1: I try to fill my glycogen stores starting the day before hard sessions or rides (for example pasta the day/evening before and oat meal 3-4 hours before the session…combined with individual electrolyte/carb drink on bike).
    But is there some way to tell how filled the glycogen stores are at the moment?
    Maybe I would have just needed half the extra carbs because the stores are already 50% filled for example…which leads me to question 2…

  • Q2: How long does it take before redundant carbs get transfered and stored as fat? And what does that process look like?

  • Q3: If my glycogen stroes are filled but I do not workout for x days (or need that energy because I have normal nutrition)…what happens with that energy stored in the glycogen stores…does it stay there happily as long as the muscles do not decrease? Or will it get used/transfered to sth (what?) and when does that process start?

Could be an interesting topic for the podcast @chad. 5 :star: by the way!

  1. No, only through invasive methods, e.g. biopsy. Non-invasive methods are still in the “promising state” [ ]

  2. Simple model is: as long as muscles can take up carbs they do. Once muscles are topped up carbs become fat. Of course, it’s more complicated but this is a valid simplification of the process

  3. there is always an equilibrium, e.g. always an exchange. And even at rest muscles burn a tiny bit of glycogen. However, when you look at the balance glycogen can sit in your muscles for quite a while. Some people carb load 3 or 4 days before major competitions because they want to avoid GI distress when eating so much close to race day. As long as passive muscle glycogen levels stay full.


Thanks, this helps to get a clearer picture! The article looks very interesting, will read later.

I guess that’s the tricky part. Already trying to look after slow digesting food. Maybe will try to stretch carb loading phase a bit.

from a practical point of view this articel is probably more relevant:

though one must say since we can’t measure glycogen levels there isn’t much we can do specifically. Just some general strategies. However, one shouldn’t overcomplicate things either.


I think you’re a little hyper-focused on this glycogen aspect. You don’t need to carb load or really do anything specific for a hard workout. Just eat a balanced and healthy carb centered meal 3 hours before a workout and you’ll be fine. Eat enough until you are no longer hungry but not full.

Also use a sports drink for high intensity workouts (Heed for example) on the bike. I’m guessing you think glycogen is why you are struggling in hard workouts. Maybe, but probably not. Hard workouts suck for everyone and if your FTP is correct it will at times push you to your max and you will “fail” on occasion. That is normal. I’d focus on your mental toughness and “brain training” over trying to reach some perfect glycogen goal.


Thanks for sharing that article :+1:! I was looking for something like that.

Thanks for your input!

Overall I’m not afraid of (failing) hard workouts. It’s more like trying to avoid unnecessary fat gain if carb intake is too high and stores are already filled. Nevertheless maybe you’re right and I overthink too much (I’m happy with my shape in general and just looking for those details to optimize). Thanks again.

I agree with @MI-XC that you might be overthinking this. There are very few, if any, workouts in the training plans that require a deliberate carb loading strategy that stretches into the prior day.

Could you share some workouts you’ve been doing and why you think that carb loading would’ve helped you complete them?

You’re all probably right with overthinking. I like the details :). Thanks.

Carb loading is mainly before those harder outdoor rides but at the beginning of SSB MV2 I wasn’t used to those 2 hour indoor workouts and my body feels similar to Nate who always stresses his high carbs on the podcast.

Last time was last week of SSB MV2 when I needed to shift workouts and had Leconte then Lamarck then Wright Peak -1 day after day after day. The last 30min of those 3x30 of Wright Peak -1 I was cooked and dialed back to 90%.

Don’t know if this was the best option: Maybe I should have skipped Lamarck the day in the middle. Maybe I should have just stopped after 2x30. Maybe it was ok to suffer through as I did with last 30min at 90% to get some stamina and with a recovery week to follow (which was so needed but afterwards gave me a good result I didn’t expect).
That’s part of the journey…to always learn and get to know oneself better with the experiences.
Sorry for the long text…but you asked :wink:

Those are three tough workouts to do back to back to back like that. I think you’re likely confusing your reason for failure on the final one. It could’ve been a lack of glycogen, but was much more likely simply fatigue. Your body is used to a rest day somewhere in the midst of those three workouts and you didn’t have that rest day.

It is, of course, possible that you are under fueling before or after your workouts - but going heavy calorie positive the day before or day of these types of workouts (i.e. carb loading) is not necessary

I’m not sure what your FTP is so I don’t know the exact calorie expenditure for the rides for you so I’ll use my numbers as an example.

Lamarck is only an hour long - as such I’d burn 1087 calories during it. If you mix up the timing of those extra 1,000 calories you burn on the bike throughout that day (both before, after, and during the ride) you should be fully even and in good shape to hit the next day. Likewise with something longer like Leconte (90 minutes) and Wright Peak -1 (120 minutes).

The only thing you should need to do differently on days with rides like these is upping your caloric intake to account for the calories you will burn. You don’t need to fuel the day before, or even multiple days before, for these durations.

You mentioned @Nate_Pearson and his obsession with carb loading - but I’d encourage you to go back and listen to when he is carb loading and when he isn’t. He’s really only described doing a true carb overload before a significant event (Levi’s Gran Fondo, Leadville, etc.). He does focus on upping his calories to account for different training volumes - but in the normal course of his training he isn’t carb loading for days ahead of time.

I’d also say - what Nate does with carbs is a bit overkill for most people - doesn’t mean it won’t work for you but be cautious about huge carb days


Thanks for your thoughts. Will think about that.

I’ve been searching for a non-invasive product to measure glycogen. I saw one on the internet, contacted them and they never contacted me back :frowning:.

That’s the dream though. If I could know when my muscles were topped off I could adjust my diet.

I’ve found a direct correlation between more carbs = easier workouts. Just don’t kick up your overall daily calories, you have to remove something or else you’ll gain weight.

@trpnhntr What’s overkill in your opinion? If I can hit 70% carbs for the day I’m happy.

For loading, I go 8-10 grams per kg of body weight (which I’ve read is optimal). If I had more BF I would lower that number.


I was more talking about what you (and specifically your stomach) can handle in the day immediately prior to a race. I think that volume of carbohydrate would put most of us on our knees if consumed in as narrow of a timeframe as you are capable of.

Additionally - @Rizzi was contemplating carb loading for regular workouts and I was trying to separate the idea of an 8-10g/kg carb load from fueling for regular workouts

As for your regular carb levels - I do significantly higher on both fat and protein than you do but the ratio I target varies based on how much of my calorie expenditure comes from my BMR and how much comes from exercise. On a day off I pretty strictly adhere to 35% carbs, 40% fat, 25% protein. If I have a larger workout those values skew more and more towards carbs.

I’ve experimented a bit with my macros and since I eat nearly exclusively whole foods I started to struggle at 55% carbs as my defaults. It was just too much volume of fruits and vegetables. It’s just so much more stomach efficient for me to have 1 avocado than 2 apples (although I love them both as snacks)

1 Like

I’ve always struggled with nutrition for cycling. I’ve always wondered if some people are more genetically predisposed to store glycogen better than others. I know guys that can ride a 60 mile ride on a 90 degree day with no food and hardly drinking anything.

For me In the heat I’m drinking 1.5 bottles an hour just to stay hydrated. And I struggle to eat enough. If I’m not eating I’ll bonk. I started recently tracking my food on rides so I can find those happy numbers of carbs/hr for me.

But even on hard trainer sessions, 90min+, I feel so much better if I’m fueling during training. I feel like body is just poor at glycogen storing.

An interesting article on what happens if you eat too lean…