This effect is nothing to be celebrated. The same thing happens to us people with anorexia. In the beginning, the body sends you all these signals in order to make you know it needs food. But, if you ignore them, it changes its strategy. The body desires so much to survive that it adapts to anything as best as it can, and in the case of a prolonged restriction it believes the best way to do it is that you have energy and are not overwhelmed by feelings of hunger so you can place all your attention in the action: in the action of getting food, which in other times would have implied an effort like going out to hunt.
That’s why you have more mental clarity. That’s why I felt more intelligent and elevated and spiritual than the rest of the world, as it happens to the people who reach this critical stage. Please, if you ever feel like that, don’t interpret it as a triumph, but as a signal of danger and that you need to get out of there as soon as possible.
It’s not the same to get to be comfortable with an IF schedule (which is totally cool, if you want to try it you need to hold on beyond the initial days to overcome the force of habit and see if your body responds well to the new rhythm), than to be like if you had shot up with something.