I'm not doubting that what you say is true, but I wouldn't necessarily draw a simple cause-and-effect arrow between a single fasting event and your improved long-term health. The fact that you even began a fast suggests you became increasingly conscious of your health at that time and were looking for ways to improve it. Perhaps you also decided at that time -- maybe even subconsciously -- that a healthier lifestyle with better eating and sleep habits would be in your interest. In other words, there is a correlation between your fasting event and your improved health, but not necessary a direct causation.
This reminds me of the reasoning used by a lot of people who've made the link between autism and vaccines. "My child was vaccinated and shortly thereafter she became autistic!" Yes, but children are also vaccinated around the age when the first signs of autism become apparent.
Human minds are incredible pattern-matching machines. Unfortunately, they're so good at it that they often deceive themselves.