So the problem with fasting is it depletes things like glutathione from the liver. Fast too much and the body will catabolise itself, ie loss of muscle mass and

So the problem with fasting is it depletes things like glutathione from the liver. Fast too much and the body will catabolise itself, ie loss of muscle mass and so on, plus things like ketosis acidosis can be a risk for some. The hygienists (1950's US based org headed by a bloke called Shelton) were into fasting and it was what Christians Lent was originally about. Now water is also a factor with fasting so if you take Islam's no food or drink during daylight hours, that type of fasting caused an increase in blood sugar levels due to the lack of fluids. When you have no food or drink parts of the immune system increase rapidly and will attack the body so you get into autoimmune disease territory. The world record is actually 382 days done in 1971 at the University of Dundee. Just water and electrolytes, but the bloke started from an obese state in the first place. He might still be alive today. There are risks with many things, not only eating (diabetes/protein rich depression) but different types of fasting. Even the paleo diet which is like a ketogenic dieting has its risks. So thats protein rich, but some chemicals like tryptophan will not be absorbed in the presence of other proteins, they compete in the gut. Copper & Zinc iirc also compete. Then there is the form so we have a gut enzyme which limits our ability to absorb ferric iron ie fe3 or iron oxide (the brown rust you get when you cook meet), but its possible to absorb lots of ferrous iron (fe2), but then too much iron can cause its own problems like internal bleeding. Ultimately it depends on what your goals are for intermittent fasting in the first place.