If your Doctor or Health Care Provider prescribes the tests, how long do I have to wait after the end of ProLon® 5-day? 29 June 2022 15:00 To have reliable analyses, it is necessary to wait at least 15-20 days after you finish this Fasting Mimicking Programme. Related articles Do I lose weight? How many times can I repeat ProLon® 5-day? I don't like the taste of L-Drink, how can I improve it?