The biggest benefit I've found to fasting is the sort of reset it provides the digestive system. I've suffered from some pretty frustrating gut health issues over the past few years, and taking a 1-3 day fast every few months significantly improves most of my symptoms. When talking to my doctor, a combination of "reduced inflammation", "digestive rest" and "gut biome health" are all things that get thrown around, but generally "Who knows, but if it works keep doing it" is the general result.