Does training without gels deplete carb reserves?

Hello everyone,

I've trained for four marathons and always used gels for any run over 13 miles, as they say you run out of carbs after that limit. Being not a beginner anymore, I have lately experimented with long runs without gels and done fine, although I've never done a whole marathon training without gels.The adavantage for me is to train running on fat and get used to the wall feeling.

My question is: do you risk reducing the amount of carbs in your muscles by doing such training? I know it is a very specific question and I should probably ask a nutritionist but I thought some of you guys could give me some advice too.

Many thanks,



  • Part of the purpose of a long slow run is to get your body to burn fat more efficiently and to improve the amount of glycogen you can store in your leg muscles and liver. So in fact, you are doing the exact opposite of what you feared - you are increasing the capacity to store a greater amount of glycogen in the future.

    I do all my slow 20 milers without breakfast and gels. If I am on a long run where I want to train sections at marathon pace or quicker, then I will generally take on some gel / other carbs to simulate race conditions . A good book that goes through the adaptations on physiology from marathon traning is Pfitzinger & Douglas, 'Advanced Marathoning' - they spell things out clearly (better than me). They also have some training plans in the book if that is your thing

  • Oh well, so that's very good news. Two pigeons with one stone: getting used to run on fat (wall-like conditions) and greater capacity for glycogen storage. Just looking at the book you recommended now.

    Thank you so much!!


  • Even if you did reduce you local muscle store you would make it up in the taper week/s before the race itself - they take days not months to refill. So the the risk, if there is any, only applies to training on the immediate days after.

    As AR says, there is a school of thought that somehow your body learns to cope with less local storage. See how it goes with, say, sunday long runs and if you are feeling too tired to complete for example a tuesday interval session two days later you might prefer to be able to keep the speedwork instead of deliberately not feeding.

  • PhilPubPhilPub ✭✭✭

    Going long unfuelled is definitely a good thing to practise, but whatever you do before or during the run, always refuel properly straight away afterwards (protein and carbs).  You should get the benefits of adaptation to fat burning from the run itself, and if you can stay adequately fuelled afterwards hopefully the rest of your training won't suffer.

    The body really does adapt, too.  I used to feel pretty low on energy when I moved into the 15 - 20 mile region for my first marathon but I'll happily manage 20 - 22 miles (at an easy pace, @MP + 60-90s) without fuelling from the evening before.  Be prepared to require an afternoon nap, even if you refuel properly!

  • speaking of napping, i find that I sleep much better when i'm running regularly. There's nothing i've found, quite like a long run to tire you out for a good sleep, so i often wake feeling quite fresh the day after a long run.

  • Thank you, Steve. Yes, I agree that it does not take too long to recover. And then again I was thinking, wait a minute, this doesn't even make sense! If you run out of carbs after 13 miles or so anyway, there are no carbs left to be depleted. Yes, ok, you take gels to reload but, again, they only last for so long. On a 20 miler I'm not able to stomach more than six gels, about 500 calories, which will cover me up to 18 (I know this is personal but let's say my average).

    You will run out of carbs anyway. And, if anything, you will deplete your fat resources, of which even a skinny person like me has more than a good reserve.

    And yes, Phil, I do make a point of eating some carbs within one hour of finishing my long run, the best time to refuel, plus a full meal rich in carbs and proteins.

    I can't take a nap though. Too many endorphines. But I do sleep well at night!!

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