It has been suggested that fasting is good for reducing inflammation and improving conditions associated with inflammation; well known fasting regimes include the 12:12 fast, the 5:2 diet, the 6:1, the 16:8 plan and the 36-hour fast.
The rules vary, as to the appropriateness of using these plans (medical advice is recommended).
This page provides a simple tool to assist in working out when you can finish a fasting period, with the assumption that you must wait x number of hours after your last meal. Simply enter the time of your last meal and how many hours you want to have to wait before you can break fast - it will then tell you when you can eat next.
Note, this tool is optimised to fasting periods of less than 24 hours - after which the results may be problematic as it does not know what day you last ate.