Hmm, for starters I began (like most people) by doing a 16:8 IF. It felt good and counting calories at the beginning helped me understand where I should “control” myself in the eating period. I have never taken electrolytes or anything supplementary and my PR is 64 hours without big problems! The most important thing is listen to your body: if you start feeling pain or some big discomfort stop and try to understand what happened. Another thing is fasting is not magic, you still have to control a bit of what you eat because in the end you need to go into calorie deficit (intake calories less than used calories). I went from 108.5kg to 95.7kg in 6 months and I’m 180cm if that matters to you.