“In order to produce glucose for energy, the body starts to use proteins stored in the body. Now, proteins are most commonly associated with one’s muscle mass, so you’re right to think that gobbling up your own protein will have a negative impact on your muscle mass. Proteins release amino acids, which can be converted into glucose; this is good news for brain, but extremely bad news for your body and physical appearance.
You’re right to say that fasting for shorter periods can and will burn fat, but after some time you will begin to burn your muscle mass because fats do not have the stuff needed to operate your brain. Fasting for a day is not enough to do that, but multiple days can and will do this, and I personally know a few people who neglect food for multiple days.
“In order to produce glucose for energy, the body starts to use proteins stored in the body. Now, proteins are most commonly associated with one’s muscle mass, so you’re right to think that gobbling up your own protein will have a negative impact on your muscle mass. Proteins release amino acids, which can be converted into glucose; this is good news for brain, but extremely bad news for your body and physical appearance.
Such a rapid depletion of the body’s proteins will result in a weakening of the entire body, diminishing muscle mass, and decreased libido. In women, this can result in a total shutdown of the menstrual cycle.” [https://www.scienceabc.com/humans/what-would-happen-if-you-stopped-eating-altogether]
You’re right to say that fasting for shorter periods can and will burn fat, but after some time you will begin to burn your muscle mass because fats do not have the stuff needed to operate your brain. Fasting for a day is not enough to do that, but multiple days can and will do this, and I personally know a few people who neglect food for multiple days.