[aerophilic]

In Graduate school I fasted for a week. It was deliberate as a cleansing activity for myself. Before this I had never really did any extensive fasting.

To directly answer your question, I didn’t talk to a doctor ahead of time, but I did make sure to drink lots of water during that period.

I remember the hardest day was day 2. For the first day, you “feel” hungry as your body is accustomed to eating, but it is day 2 you are genuinely hungry. However, per the article, after about the third day you simply don’t notice yourself being as hungry anymore.

I noticed then (and notice now when I fast) positive effects on mood, and ironically energy.

The only drawback I have noticed is that the first meal after a fast, especially if a large carbohydrate based one, seems to have outsized effects on drowsiness.

[woleium]

The body uses a lot of energy processing food, so once you are in keto and not processing then you should in theory have a burst of energy.

This sort of makes sense from a hunter gatherer survival selection pressure too.