Refueling during fasted run?

  • Creator
  • #41900


    I’m currently reading into fat adaption and nutrition both on this site and in TftNA, and have had some helpful realizations.

    I have preferred running fasted for the past year or so before having read into any of the literature as to its role in fat adaptation, so I believe I may be making good progress towards fat adaption as is. I have noticed, however, that right around that zone of 2-3 hours I either bonk or come close to bonking.

    TftNA recommends refueling carbohydrates around 90 minutes into a long Z1/Z2 workout because of their role in lipolysis. Does this recommendation change at all for fasted runs? Thanks!

Posted In: Nutrition

  • Participant
    Rob Sterling on #41901

    Worth listening to the latest episode of this podcast, its 3 hours long, based on a lot of solid evidence, and they answer this question well in the first part – essentially, recommend that fasted runs still need fuel at about 90 minute point.

    im at the 2 hour point, so much info its unreal!



    deckersdan on #41904

    Thanks so much, Mike. I’ll check it out!

    Anonymous on #41917

    This is true and not. Beware of any hard and fast rules, because it really depends on the individual and their current training state.

    One of my clients regularly does 5-6h runs fasted, and he’s also very, very fast. On the other hand, there’s no way that I could do that.

    I think a better guideline is to make the training worthwhile. As soon as you start feeling bonky, maybe push for 15 minutes or so, but I’d be surprised if there’s much benefit after that. Some kind of stimulus has been achieved at that point, so I’d rather eat and continue on with the session.

    In contrast, if someone gets to 90 minutes and feels fine, and if the goal is a fasted session, then I don’t think they need to refuel just because of a general rule of thumb. That would be working against the goal of the session.

    Anonymous on #41941

    I concur with Scott Semple’s comments. In particular: These kinds of questions are not of the yes/no type. They are highly individual. You need to make these sorts of decisions based on your own (not someone else’s) experience. Here are a few guide lines I’d offer.

    If you are bonking at 3 hours then eat something. Bonking is not a desirable energy state to fall into because you will be reduced to walking and the training effect will be greatly diminished.

    There is a balance between fasted training vs recovery and fasted training vs performance. If you train in a fasted state to cause extra glycogen depletion you WILL improve fat adaptation. But there is a very good chance you will extend the recovery time between workouts. This is why we recommend fasted training during only Z1-2 workouts during a period where performance or delayed recovery is not going to have a serious downside. We have a little saying that we use: “Train on fat. Race on carbs”. By race we mean any important event where performance really matters.

    In the end you will need to play around with the balance mentioned above. Some days it will be appropriate to dig way down into glycogen depletion (sans bonking). Other days you’d be wise not to.

    I hope this helps.

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