Fasting Clarification

Been off flour/sugar for 3 weeks now. Also been doing 16:8 fasting that time except for one day. It’s been going well and I’ve dropped some weight.

My questions are: How long is it recommended to keep fasting? Do you mix it up and how do you decide? Thinking I may have missed something.

Also, if I were to eat something with flour or sugar in it, does that restart the entire detox/withdrawal process? I wonder if I accidentally ate a salad dressing that had sugar in it at a restaurant we ate at or something causing my hunger lately. Curious how that works.

Thank you!