I gave a lot of thought to the protocol I will be using to test fat oxidation again in 2 weeks, which you can see below.

In particular, there are some important considerations to make, as our recent diet impacts the test to a great extent (even just our breakfast before the test can reduce fat oxidation up to ~30% if I recall correctly).

Eventually, thanks to a few good practical studies that Dan Plews and co-authors have done, I have narrowed down the range of options, e.g. no need to be fasted, which would be unrealistic for me (I will have about 5-600 kcals of protein and fats before the test) and then I will do a double sub-maximal ramp test with carb intake (40g) between stages.

This way I can get a "best case scenario" in terms of potential improvements in fat oxidation, during the first stage, which I think is important because I want to see if the dietary changes were all for nothing, or not.

The idea behind having 40g of carbs between stages and then test again after 20 minutes is to get some insights on how quickly these things change (even just answering these question: do I mess it up with a gel before training, or not? by how much? what would be the difference in a race, after having a higher-carb breakfast?).

Looking forward to seeing how this goes.