en.wikipedia.org
An example that you can fast for more than a year and live - on one condition: (morbid) obesity. He lost 276 pounds (read the page, and then do some research). I suggest dr Jason Fung's YT (
).
If you don't have an ounce of fat tissue though, I'd discourage you from fasting.
My longest fast was for about a week, and even though there was a lingering sensation of hunger, I actually did have energy to go on. 100 hrs is what, c. 5 days? Pointless if you're a beginner. Have shorter fasting periods, eg. 24, 36, 24, 36, 48, 36, 48, 36, 48, 60, etc. Have some breaks, be it a few days, a week or something. For me 36 hours is just the introdution, 2nd and 3rd day is the least pleasant, but 3rd going into 4th... oh yeah.
I have read elsewhere, beyond 48 hours it is pointless and actually starts to be harmful, and you still get all of the benefits you mentioned above anyway.
I'd love to read this source. Because in a world where there is a culture of eating, and sometimes binge-eating, eating when you're bored, down, happy, pensive and what not, "have a snack" is the answer. Extra pounds / kilos that come with it? Ah well.
And this "ah well"? Research what (morbid) obesity leads to.
Just make sure you are not starving yourself,
If one does not take carbs, insulin level drops and the body is able to get to its fat tissue = no starvation. BUT, salt is a must as you urinate sodium, and carbs don't store water in your body.