Questions leading from the Podcast

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  • #44400

    Rebecca, Scott.
    thanks for the excellent podcast about nutrition/fasting etc. There was a lot of information, but I wonder if you wouldn’t mind clarifying a couple of things- there are a number of different voices around, so some semblance of unity of voice might be useful.

    (As ever, in training as in life, I suspect the answer will be “it depends”).

    1)- Fasted running. Does it need to be fasted for it to be effective in educating your body to preferentially run on lipids rather than carbs? From my previous reading/understanding, it is *better* to do this kind of training in a fasted state, (and you reap greater benefits in a shorter space of training), but could you run in a “lipid preferential” zone during the day and still get the same training effect?

    2) There was mention about intelligently planning when to do a fasted workout during the week. It was interesting to hear you mention that there is a high stress response to fasted training… in the past I have used it as a “recovery” workout, on a day when I wasn’t training hard. Was I unintentionally getting a higher stress response everyday?!
    If Fasted training is a “hard” workout in terms of stress response, evidently I shouldnt be doing it on a recovery day. Is there any detriment to doing a fasted session in the morning, and then a carb based harder intensity session later in the day?-

    and perhaps leading on from this- (3) there seems to be a misunderstanding/myth that if you are training in this way that you should *never* do any type of training beyond your aerobic capacity limit.
    (“oh no! I went for a run at 160bpm last night, I’ve undone all my hard work for the last 4 months”).
    please tell me that is nonsense. Surely your body is intelligent enough that training in a fasted state is fine, and as long as you continue to do this consistently, training at a higher intensity simply trains a different, but complimentary energy system without compromising your lipid preferential exercise capacity.
    (apologies if these questions have already been asked)


Posted In: Nutrition

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    Rebecca Dent on #44425

    Hi Tim,

    Thanks for your great questions. Yes as ever with nutrition there is always a lot of information/research surrounding the topic, and context is king when it comes to application.

    I’m going to attempt to answer your questions and I’ve asked Scott to step in and help, so hopefully we can have his input.

    Question 1)

    As we tried to highlight in the podcast regardless of dietary intake simply carrying out endurance training per se, at the lower intensity heart rate zones, increases our bodies ability to utilise fat as a fuel source (fat adaptation). There is limited data to show that carrying out fasted training translates into superior performance benefits. However both Scott and myself have observed when those who do carry out fasted training appropriately, this person sees benefits to their training in terms of; can start to go further over time without eating during their fasted run, reduce desire to eat on non fasted low intensity runs, reduce cravings for carbohydrate/sugary foods. So potentially yes you could reap greater benefits in a short space of time but this will also depend on the training status of the individual. I’m not sure there is a ‘lipid preferential’ zone during the day. The lipid preferential state will come from the intensity of the training session i.e. zones 1 & 2 low intensity and potentially you can influence this state via carrying out the training session a fasted state and manipulation of dietary intake.

    Question 2)
    Generally if you were simply carry out a recovery session fasted, this is not going to create a higher state of stress. I would assume the recovery session was of low intensity and for a short duration? Depending also on the time of day (which I again assume was first thing in the morning prior to breakfast) at this time your muscles are still going to contain a source of glycogen. It is the low/depleted glycogen levels in the exercising muscles that have a greater influence on the increased stress response (again assuming you are not on a low carbohydrate/keto diet and ate carbohydrate in your recovery meals post exercise the day before).

    I will let Scott answer this final part of your question in terms of carrying out a strength based session later in the day after a fasted session.

    Question 3) I’ve not heard of this myth so will let Scott answer this question. However it sounds like a myth as when training for the mountains / ultra endurance you need to train both energy systems (aerobic and anaerobic) and get strength to support your efforts of your objective. You will just need to be strategic about this training.

    I hope thats be of help?


    Anonymous on #44429


    I’m pleased that you found the “fasted training” podcast helpful. There is a bewildering amount of, sometimes conflicting, information regarding all aspects of nutrition. While we are interested the science of nutrition and it can be helpful to read scientific studies, there’s not so much of that supporting evidence when it comes to healthy endurance athletes. Hence, our heavy reliance on what we’ve observed first hand when working with hundreds of athletes over 30 years. So….my experience leads me to answer this way:

    Q1) Doing fasted training first thing in the day is just an easy way to achieve a glycogen depleted state and hasten the fat adaptation process. You could perhaps get a similar effect training later in the day several hours after a meal but I doubt the effect would be as powerful. Another way to do this would be to do a high intensity glycogen depleting workout in the AM then do a longer low intensity session later in the day. As Rebecca said the lipid/glycogen preference is going to be mainly determined by the intensity unless. However we often see folks who are very poor fat utilizers who are using 90% carbs/10% fat even at their slowest walking pace. For these folks fasted AM training will speed up the fat adaptation process.

    Q2) You are the ultimate arbiter of the efficacy of any training or dietary strategy. You may need to experiment on yourself. When in come to recovery sessions I don’t recommend them to be done fasted. However, as Rebecca said these are probably short and very easy so should not be too stressful. How do you feel after these? Try doing some fasted and some with fuel before. See how you respond. As you said: “It depends” and there’s no one size fits all prescription.

    Q3) Is there any detriment to doing a fasted session in the morning, and then a carb based harder intensity session later in the day?- It depends on your goal for the training. Chances are good that your performance will be impaired during a high intensity endurance session done late in the day after an extensive fasted AM session.

    Myth: I’ve not heard that one either. Each training session will ideally have a goals or small set of goals you hope to achieve. But training above the AeT will not reduce your fat utilization unless the volume of high intensity training becomes large relative to the low intensity work. We see (and supported by the Stephen Seiler studies) the most successful endurance athletes using the 90/10 balance between low and high intensity volume.

    I hope this helps,

    ttbudd on #44712

    Rebecca, Scott, thanks so much for your answers.

    The main question I have after your responses pertains to the second last para of Scotts reply.
    Specifically about the “extensive fasted AM session”.

    by this are you saying that in an adapted athlete, the fasted ‘fat adaptation’ session of low HR work can/could/should go on for an extended period of time and be the main session of the day? If so, then yes, I can see why a high intensity session later in the day might not be optimal.


    If we are looking at someone who is relatively well adapted, but wants to keep on top of their aerobic capacity- 3x a week 30min-1hr runs at zone 1 (which should be pretty easy), and thus probably wouldn’t be classed as a “hard workout”- so a High intensity session later in the day (strength session, explosive hill session etc)- if correctly fuelled would be fine?

    (as ever, I can already hear the answer being “it depends!”.

    Anonymous on #44858

    If we are looking at someone who is relatively well adapted, but wants to keep on top of their aerobic capacity- 3x a week 30min-1hr runs at zone 1 (which should be pretty easy), and thus probably wouldn’t be classed as a “hard workout”- so a High intensity session later in the day (strength session, explosive hill session etc)- if correctly fuelled would be fine?

    I don’t think that the short easy runs early in the day will have much of an effect on the second session. Because they are both short and easy, the extent of the depletion will be minimal and eating in between workouts will likely restore glycogen somewhat, perhaps completely.

    Before the second session you would also want to make sure that you’ve eaten to ensure that you’re “topped up”. When I’ve made the mistake of a hill sprint session without being properly fueled, my power output suffered and I finished feeling “bonky”.

    I think what Scott was referring to wasn’t a short, easy fasted session but a longer session targeting glycogen depletion and fat adaptation. For longer depletion sessions, the depletion could be severe enough that a high-intensity second session would be compromised. But you’d likely be able to feel the difference.

    Mariner_9 on #54812

    I have a question on alcohol consumption and training.

    My alcohol consumption equates to about 1/2 a glass of wine or 1/2 a bottle of beer each week. Is this volume of consumption likely to impact my recovery? And as a follow-up, is there a way to time the consumption to minimise the impact? (e.g. don’t imbibe on a day with a higher training load)

    TerryLui on #54864

    Is this volume of consumption likely to impact my recovery?

    I would imagine to set your body up for greatest success, eliminating alcohol completely from your diet during training and during the objective will be most optimal.
    In between training programs / post-trip…go celebrate!

    Of course…everyone’s ability to metabolize alcohol differs, perhaps try adjusting your intake volume and pay attention to how it impacts your recovery?

    Mariner_9 on #54960

    Thank you, Terry. A controlled trial makes sense though I suspect it would be hard to isolate the impact given the number of other factors and their natural variation (sleep quantity and quality, work-related stress…the usual stuff).

    I am hoping that the quantity is sufficiently modest so as to have no significant effect. As good Scotch is all but impossible to find in BC, the chances of my consumption increasing are very low! 🙂

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