(I have previously posted about intermittent fasting here and here. What follows is general - pretty comprehensive it seems to me - info about the benefits of fasting.)
[This person fasted when they caught covid] and it was gone completely in a couple days, absolutely nothing. [Study of one] Some of the many benefits of doing occasional extended fasting: Blood clotting is reduced and blood clots and arterial plaque are reabsorbed into the body. Blood pressure is quickly and dramatically lowered.
Fribrosis/scarring is reversed over time and telomeres are lengthened, which also helps with lung fibrosis.
Fasting increases nitric oxide.
Fasting stimulates phagocytosis, the ingestion of bacteria, plaques and viruses by the immune system. It will also remove any 'foreign material' that is not supposed to be there.
After 72 hours or more fasted, your body recycles large numbers of immune bodies and creates new ones, rejuvenating your entire immune system.
Vitamin D plasma levels are increased, and vitamin D in turn increases autophagy.
Fasting increases anti-aging Yamanaka factors!
Fasts from 36-96 h actually INCREASE metabolic rate due to norepinephrine release!
Weight loss from fasting only loses10% lean tissue and 90% fat compared to the typical 25% lean tissue and 75% fat lost when calorically restricting for long periods. The hunger hormone ghrelin lowers with extended fasting and rises from dieting.
Blood sugar and insulin are lowered, allowing white blood cells to move more freely throughout the body and do their job. Ideal blood sugar is around 80. Some viruses activate glycolosis (the release of sugar in the body) and clinically it has been shown that decreasing glucose metabolism in the body weakens the influenza virus.
Thymus is regenerated, which suppresses aging and renews the immune system.
When you move out of MTOR your body shuts down the building blocks of the cell which are used to produce organelles and proteins. This means the mechanisms needed by viruses to replicate are by and large unavailable when you are in a deeply fasted state.
What breaks a fast? Anything with protein or carbohydrates in it will break a fast, though if the amount is tiny you will go back into ketosis very quickly. Most teas and herbs are OK. Most supplements and meds will either break ketosis directly or contain a filler that will. Many medications are dangerous to take while fasting so you may have to talk to your dr. about discontinuing them during a fast.
Fasts of several days will not affect short term female fertility and may increase long term fertility, especially in women with PCOS.
Does fasting lower testosterone? No, it raises it when the fast is broken by increasing lutenizing hormone and helps build muscle by increasing insulin sensitivity!
The hormone Leptin is an immunomodulator that keeps the body from attacking itself and obesity causes leptin resistance. Fasting very quickly reduces leptin resistance and leptin levels and one day of fasting can cut your leptin levels in half and gets your immune system working properly again!
Does the body preferentially prefer glucose as a fuel? No, your body always runs mainly on fat except for brief periods of very intense exercise. Your brain also prefers to burn ketones at a rate of around 2.5 to 1 when they are available in equal quantity to glucose.
Fasting stimulates the AMPK complex and activates autophagy. Autophagy (literally self eating) will cause cells to recycle foreign matter such as viruses and kill cancerous and senescent cells. AMPK does many helpful things in the body including activating the body's antioxidant defenses.
Deep ketosis virtually eliminates chronic inflammation in the body. This can offset the life threatening symptoms of viral pneumonia which effectively kills you through inflammation. This also creates BHB ketones in your body, which also help your immune system and anti-oxidative system, especially in the brain. Ketones also provide an additional energy source during infection, which is critical when trying to fight off a bug. In fact you can have as much as three times the total energy available in your blood when you are in deep ketosis, or even more.
It increases mitochondrial function and repairs mitichondrial DNA, leading to improved ATP production and oxygen efficiency and thereby making cells better able to fight off infection. Increased mitochondrial function also has the added benefit of increasing your metabolism and cancer prevention!
When you fast, this stimulates apoptosis in senescent or genetically damaged cells. This kills these cells off completely. Senescent cells are responsible for the effects of aging and are the root cause of the development of cancer. If it were possible to destroy them all it would completely stop aging and cancer. That is not possible but fasting can help limit these effects by killing off many of the affected cells and limiting the future effects of aging.
Fasting also releases BDNF and NGF in the blood which stimulates new nerve and brain cell growth, helping a great deal with diseases like MS, peripheral neuropathy and Alzheimers.
In fact, the biochemical regulator of BDNF production is beta-hydroxybutyrate, which is the same ketone the body produces to nourish the brain while fasting.
Fasting also increases telomere length, negating some of the effects of aging at a cellular level.
A fasting mimicking diet for 3-5 days in a row also provides many of the same benefits as water fasting. FMD usually has 200-800 calories, under 18 g of protein and under 18 g of carb.
Exogenous ketones can aid with fasting, making it easier in healthy people and allowing some people with specific issues to fast in spite of them without worrying as much about hypoglycemia.
Children, pregnant or nursing women should not fast for periods longer than 16 hours. People with pancreatic tumors or certain forms of hypoglycemia generally cannot fast at all. Type 1 diabetics can also fast but it is more complicated and should be approached with caution as it could lead to ketoacidosis. Those with Addison's disease may also be unable to fast without liberal use of exogenous ketones, depending on severity. If you experience extreme symptoms of some kind, especially dizziness then simply break the fast and seek advice.
This list compiled over years of research by the user known as Pottenger's Human on youtube but feel free to copy and paste this anywhere you like, no accreditation needed!
My channel which will always contain an updated version of this list of fasting benefits on the community tab. I also have playlists on fasting and health topics.