Having been burning Ketones more than Carbs for more than 2 years now, i can absolutely attest to that.
Previously i had to use Caffeine and occasionally Ephedra to stay properly focused on programming tasks. But the people around me often thought i was angry and annoyed easily, that is completely the opposite now that i'm "on" Ketones.
Its unlikely that depriving your brain of fuel is having a positive effect on concentration, but since eating carbs triggers insulin, which supresses the effects of adrenaline, you might just be experiencing the benefits of not saturating your diet with sugar.
The brain is not being deprived, rather it's deriving it's energy from a different source -
> the brain starts burning ketones in order to more directly use the energy from the fat stores that are being depended upon, and to reserve the glucose only for its absolute needs [1]
Additionally -
> Because the brain can only power 70% of its action on ketones, glucose will have to be used no matter what. However, because glucose can be derived from non-carbohydrate sources such as protein, a low carb or no carb diet does not starve the brain of its required energy. [2]
And your absolutely right in regards to experiencing the benefits of removing sugar from the diet.
I meant to say it's primary fuel source. Will look into this more, but I would think avoiding suppression of epinephrine has to account for some of the effect of cutting to a no/low carb diet.
For me personally - a significant difference. My productivity has increased due to rarely incurring cognitive fatigue due to fluctuating energy levels (i.e that afternoon slump after lunch goes away, skipping a meal has little or no consequence). I can code for 8 straight hours without having to eat where before if I skipped a meal I'd start getting hazy.
Additional benefits include weight loss while eating as much as you want, never getting hungry, being able to do a 10km run on an empty stomach and still be full of energy ..
Depends. I find myself more alert for some stints of time while in a ketogenic state, but on the other hand, have difficulty falling asleep (as in, normal day I'm drop dead asleep at 11-12pm, while in keto, I'm sleepy (very sleepy, groggy) but it is common for me to be awake at 2-3am. Wake up times is the same.
Not sure what is best to be honest since lack of sleep brings a lot of problems by itself.
(Ketogenic = High fat, carb restricted diet)