I mean, based on my extended fasting experience I'd say it's something that's worth exploring. I can't speak specifically to memory, but the mental clarity whenever I fast longer than a few days tends to be awesome.
A seven day fast is something I'd encourage everyone who's otherwise healthy to try at least once in their life.
I tried fasting Tuesdays and Thursdays for a few weeks in college. A couple weeks after I stopped I had severe and sudden dizzy spells for months. I’m not willing to try again unless I go hand in hand with a doctor.
That sounds interesting. Do you have any tips or guides to get started, or is it more like “just stop eating”? I have never fasted for more than some hours before.
I'd start with "just stop eating" and then solve for any issues that pop up for you because people have a lot of different reactions. For me, I do alternate day fasting... sometimes 2-3 days of fasting in a row. I had some common issues such as not being able to sleep and diarrhea while fasting. So instead of 0 calories, I eat a bowl of oatmeal (high fibre) on my "fasting days". Also, when weight training while fasted I'd feel so light-headed I'd have to stop. But I fixed that by drinking 1 bottle of Gatorade (some calories + hydration + electrolytes) before exercise. You'll just have to find what works for you. Other patterns are 5:2 (2 days of fasting) and one-meal-a-day. Sometimes after a break from fasting, I'd get too hungry the first day back on fasting so I'd ease into it with one-meal-a-day.
You should have some salts to keep well hydrated, also be healthy and don’t have any problems like diabetes, or with your kidneys. Anything over 36-48 hours would be better to check with a doctor first.
The only times I've got dizzy when '24h water fasting' are when I've been eating normal/high amounts of carbs in my diet around the fasts.
I've been doing a few days/week of 24h water fasts again, but on a very-low-carb diet, and can report no dizziness whatsoever.
An additional benefit (also mentioned by others) is that I don't have any insatiable hunger pangs on the water fasts (which I did when I attempted them on a normal/high carb diet).
Obviously your mileage may vary (etc etc), but for me, it's all about removing carbs. It's the difference between water fasting being (honestly) easy .vs. A herculean feat that I couldn't manage.
A seven day fast is something I'd encourage everyone who's otherwise healthy to try at least once in their life.