"Who cares what it is.."? Odd thing to say. It's not short nor is it simple. It's intense. And you can kill yourself from re-feeding improperly, not to mention drinking too much water and losing too much Na and K.
It's irresponsible to just throw the word "fasting" around. You must define "fasting." Some people think consuming only maple syrup, lemon juice and cayenne pepper is fasting. True fasting in water-only induced ketosis until it's broken, in a rested state, while being supervised, in appropriately selected individuals.
I highly doubt even the most weird "fans" of this random Ruskie who's mean to people have the guts to do a water-only fast anywhere near the 40 days he was talking about. I doubt he even did it himself.
Warning to those who are dumb enough to try it on their own because gbold is your new cult leader: do your research. There is only one legal clinic that does this in the Unites States, True North Health, and one in Costa Rica called the Tanglewood Wellness Center. Tanglewood is run by Loren Lockman. If you do it on your own, you're likely to do it incorrectly if you have no experience.
There are videos of people complaining about Lockman but he often uploads new videos of his newer clients on his channel who share their stories.
Fasting: An Ancient Solution for Modern Problems
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Fasting is water fasting or breus protocol which includes some juice he clarified this many times.
Many of us had tried it including me for 10+ days, it's not that bad. It can be dangerous if someone is already severely low body fat already because ketones will have nothing to feed on.
If you are used to pounding your face with sugar all day long and not exercising and don't have will power, of course it will be much harder.