Title says it all.
I used to eat 1 egg pre-meal in fear of refeeding syndrome when I was only doing OMAD. Having done three 48s in a row now I’d have to say do practice a safe refeed for 48s and up. On my third one I got cocky and ended the fast with a binge midday and later another binge at night. Only a total of maybe 1500 calories but still got bad heartburn after and was still burping in my sleep. Never again.
My advice is whether you’re doing OMAD or something above that do take some precautions and break your fast safely just to develop the habit. A Broth cube and egg soup is fine.
No. Even after a few days it’s not an issue.
I’ve eaten normally/larger than normal after a 6 day fast. I was fine. Might have some stomach discomfort as things come back online, but really not much else.