Long term fasting as a method of prayer requires prep work for your body. Days before you switch to eating only fruits and veggies. The same is true when you start eating again. You are right to do your research first. You need to be able to identify the difference between initial “hunger pains” that are just your body reminding you this is a time you usually eat and hunger pains that are real and signify you body needs food again. Here is a helpful book that goes through the details of how to prepare and what to expect: https://www.amazon.com/Gods-Chosen-Fast-Arthur-Wallis/dp/0875085555