Is a short-term fast beneficial for maintaining good health and extending life expectancy?

Question

This is claimed in Sweden's second-biggest newspaper.

My translation: "I have started to short-term fast.[...] The reason is that lots of world leading scientists that study aging and the brain has implanted in me that this is the best and cheapest method apart from exercise to maintain a good health."

The idea is to stop eating for 16-20 hours "a few times per week". Water is ok, no nutrition is allowed.

This is claimed to increase the brains production of BDNF. Decreasing overall intake of calories with 20-40% of current rates supposed to be beneficial against dementia, cancer and heart-disease. The reason is claimed to be that our cells go into survival mode when we lack energy, this in turn executes a bunch bodily functions that are beneficial to us.

They also claim nothing can go wrong because our ancestors did this for millions of years. And the reason nobody talks about this is that drug companies are evil and greedy.

They claim 700 scientific articles support the claim. No sources though.

Could someone point me to any scientific sources that support this claim?

Answer 1

I believe what you're referring to is Intermittent Fasting (Wikipedia):

Intermittent fasting (IF) is a pattern of eating that alternates between periods of fasting (usually meaning consumption of water and sometimes low-calorie drinks such as black coffee) and non-fasting.

There is evidence suggesting that intermittent fasting may have beneficial effects on the health and longevity of animals—including humans—that are similar to the effects of caloric restriction (CR). There is currently no consensus as to the degree to which this is simply due to fasting or due to an (often) concomitant overall decrease in calories, but recent studies have shown support for the former. Alternate-day calorie restriction may prolong life span. Intermittent fasting and caloric restriction are forms of dietary restriction (DR), which is sometimes referred to as dietary energy restriction (DER).

Scientific study of intermittent fasting in rats (and anecdotally in humans) was carried out at least as early as 1943.

See also, here and here for studies that have been performed on the subject. If you need more sources/studies have a look through the sources at the end of the Wikipedia article.