It's great to see so much literature and research into this topic, explaining more specifically what's going on with intermittent fasting; the science to what I think I discovered by chance in my college days...
When I was stressed by a workload (studying for finals... or working a mentally demanding project) I would skip dinner, and get a lot more done those nights; I'd have a noticeable spike in productivity, focus and mental fortitude. When I became aware of this, I reduced the amount I ate for dinner on a regular basis and often found I had more energy, slept better and felt happier, or somewhat less 'brain fog' for lack of a better term. For a while I thought this was sugar or salt related, but then I realized it was 'snacking' related... that I'd often snack on carb heavy things while watching TV, usually at night, and this could have the opposite mental effect.
From what I've gathered, basically this boils down to our chemistry, in evolutionary driven processes. In the way back days when a group, or tribe was short on food (fasting not by choice), the members with heightened mental ability (brains that focus mental acuteness on solutions, and give the energy to follow them through) thrived and saved the group from starvation by innovation, ideas and plans that would produce, find and secure food for themselves and others... over time, those who could do this were rewarded so much that this ability to have a heightened mental state from fasting manifested in us all
Pretty neat stuff... I wish we taught this to our children in school. Would be helpful for life, to know our bodies better and how we react to not only what we eat, but when we eat it.
