I think the hardest thing for people to get past is the hunger which I believe is just a conditioned response for the most part. When we have been eating breakfast and lunch for the past 30 years and we happen to miss those morning feedings typically we get the "Im starving" feeling but as we know we really aren't starving and are far from it.It's the opposite for me, I am much more energetic and happier. I am sleeping better too. Now this is compared to a regular cut. I can't say what will happen when I increase the calories and try to gain back a little weight. Good things I would assume though.
The energetic feelings we get from fasting is our bodies normal response to it. When you are in a fasted state it signals cAMP (cyclic adenosine monophosphate) production which results in the feeling of being alert and energetic. Also by being in a fasted state for the majority of our day the sympathetic nervous system becomes dominant and blood sugar levels remain stable.
It is no surprise that once we overcome the "hunger" feeling we feel energetic, clear-minded and wide awake during the day