Tim:

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,
Scott

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.

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?