When I did my first long fast, after a certain point, it got a lot easier. I know that seems crazy, but it was true. The second day I thought was the hardest, the third not so bad, and then it was smoother.
The longest fast I ever did was 5.5 days, though. I started getting dizzy when I stood, so I bailed on the fast. I did a ton of 4.5 day fasts for a while.
Some people only recommend about a 3.5 day fast (and I’ve done a lot of those too), as I think that’s when your growth hormone and metabolism hit a peak. After that, some are concerned with a loss of muscle, too. I’m not sure about that, but Dr. Phinney is against longer fasts.
If you’re not getting really cold, it’s probably not a big deal. I was getting so cold, I couldn’t touch myself.
Maybe a 3x/week (Mon, Wed, Fri), then wait until Tuesday night to start the longer fast? That would give you Sat, Sun, Mon, Tues to recover. Then fast until Saturday morning? Or you have a normal week, then the 3.5 day fast.
This also depends on what effect you get after a longer fast. I used to eat a normal meal after a 4.5+ day fast, but it wreaks havoc on my system. I have to go to the bathroom a ton for hours. So, I learned ending a fast on Friday night is not good. I end now toward the morning. And I even try some gentle break in (eg, some broth and an egg maybe, then wait to have more).
Not everyone gets these effects, though.