> 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.
[1] http://en.wikipedia.org/wiki/Ketosis
[2] http://www.nootropicmind.com/better-brain-fuel-source-carbs-...
http://eatingacademy.com/nutrition/ketosis-advantaged-or-mis...