I.F. frees up the digestive system to work on deep seated health issues. Natural Hygiene from the 18th century recommends fruits (because they are pre-digested) before noon, one meal afternoon (doesn’t need to a big meal) to engage digestive system followed by smoothy type meals (almond milk and berries) I find to be the best diet. Supplemented with something like cruciferous vegetables cooked in coconut milk and curry powder or an apple etc. supplies enough nutrients.
Natural Hygiene was university training until the 19th century when big pharma deemed fresh air, sunshine and whole foods not a science, closing the universities ensuring research money only to synthetics.
But Helen White did preserve it as part of their religion if your interested in their food regulations. It’s been taken to the extreme but then so has her prophesy legacy.