I swear I will get to some numbers and thoughts about how this diet is working for me, but first I want to briefly mention something near and dear to my heart. Nuance.
I am highly skeptical by nature of diets and nutritional interventions that are suppose to increase performance. The main reason being that I look at the science and a majority of the time the data for a given diet or training change is just not there. The most common reason for that is because scientific studies by their nature must be limited scope. What do I mean by “limited”? Well when you design a study you have pick a primary outcome on which the experimental design is based. As an example, if maximal oxygen consumption was primary outcome then the rest of the study needs to be designed in such a way that maximal oxygen consumption measurements are never compromised. In practice this means that tests to look at performance over 2 hours or running economy or lactate threshold may not be ideal or possible at all. Furthermore, the results cannot be extrapolated to a different outcome. An increase in VO2max does not necessarily mean an improved in marathon time. Over interpretation of the data is considered a scientific sin and an important part of the peer review process is to make sure that the conclusions are fitting of the data. Of course in the popular press similar limitations are not always present and every couple of months we get a story citing how this diet or this exercise regime is now the end all be all. It lacks nuance.
A second problem with many large exercise or diet experiments is that the intervention itself is not robust enough. Lets think of an example. Suppose your hypothesis is that endurance exercise improves some biomarker for disease, lets just say fasting blood glucose. So you design a study in which pre-diabetic individuals are given an endurance exercise training program and you will follow up with looking at fasting glucose. Sometimes such a design proves problematic because the subjects do not always.
I bring this up to say that the data is not clear on whether high fat diets improve performance, but the published data might NEVER be specific enough for your particular situation. The lack or moderation of an effect might be merely a consequence of the way that we have to do, and appropriately interpret science. So thats one reason why this skeptic is cautiously optimistic about this whole self-experimentation.
Of course if it does there will be plenty of caveats and nuance needed in the interpretation.