Dude I know this is r/fasting but 19 is pretty young. Your still growing. I’m not saying don’t fast, but I’d definitely talk to a doctor about it. And take every precaution while fasting. Snake juice, hydration, everything.
I wrestled in high school and dieted to ‘make weight’.
My father was 6’4” and my brother is also. I’m 5’9”.
I definitely wouldn’t do a 40 day fast. Check with a doctor. I just completed a 36 and 45 hour fasts, so I’m a proponent of fasting, just not at 19. Obviously you will do what you like, but why not get more information?
>eventually was fine after a little bit of salt
Do even you have a plan on how to systematically supplement electrolytes, vitamins and other nutrients because that sounds more like trial&error!