OK, as someone who does 5 day fasts most months: 1. You probably made it more difficult with this vitamin powder stuff. It made your body expect more calories, especially carbs because they tend to be hidden in that stuff. I wouldn't be surprised if it was equivalent to sugar water, or nearly, even if nothing of the sort was listed in it. You probably could have hit ketosis a day or day and a half sooner, or you could have eaten keto for a few days before to prepare, making it even easier. I'd consider a trace mineral supplement instead to help you concentrate and not lose too much water.

2. Break the fast with a cup of bone broth, and about 2oz of lean meat. Then 2ish hours later you can have a bigger meal and be back to normal. This will keep you from feeling too intense a need to feast and will keep your blood sugar from spiking when you eat a normal meal again.

3. Use the fasting to do things like kill insulin resistance but don't worry about your poundage, that will take care of itself.

Just FYI. My fasting mentors are Thomas DeLauer and Dr Mindy Pelz. I find them super knowledgable.