In this video Dr. Peter Attia gives a testimony about his transition to low carb eating, some of the reasoning behind it, and how it effects his mental and physical performance.
youtube.com/watch?v=hB7aGnf...
I've also felt the mental effects that he describes around focus, but that was mostly in a fasting state (e.g. ketosis brought on through starvation). Likewise with physical performance (fasted for 24 hours and played intense basketball with no negative side-effects).
Have you felt either the physical or mental benefits of being in deep ketosis?