Fasting truly comes down to what will help you adhere to your set nutrition plan the best! Some people do 1 day per week, some do 2.
Others do “intermittent fasting”, which is where they give themselves only a small window each day to eat all of their calories! This is a great way for people to get away from snacking and the extra calories that can wreck their intake for the day!
Some fast for 16 hours and eat in an 8 hour window, others will do 20 and 4, and I’ve even seen some that like to get all their calories in one sitting at one meal!
The point is, there’s a lot of different ways to do it, with very minimal extra impact to fat loss. The idea is to help you stick to the calories and macros you should be eating each day!