Is it possible to do 16/8 from monday to thursday/friday and eating normal at the weekend or would the effect be ruined?
Some people do it, but I think it’s important to be consistent the entire week. You can very quickly and very easily undo 5 days of deficit/progress over the weekend.
Personally, I do a mix of 16:8, 18:6, and OMAD. That keeps me on track.
Define “normal”. If you mean eating 3 full meals, dessert, multiple snacks, drinking soda and alcohol freely, eating during the day and night, eating whatever you want, then no. If you mean, let’s say, 3 meals, one dessert or snack, and one occasional drink, that could work. You will lose weight slower, but you will probably not feel so restricted, and your social life would be more enjoyable.