You can certainly do this! I’m a bit surprised that you’re feeling weak and tired but you should get through that in a few days. Fyi you will likely need to get on electrolytes in a few days. Your store of them runs out between days 4 and 5. I just finished a 55 day water fast and was a dummy and wasn’t aware of this. I crashed (numb, tingling extremities, heart palpitations, weak, very lightheaded, even dizzy) half way through day 4 but after eating some pink salt bounced right back.
I recommend checking out the info on reddit r/fasting, especially the wiki on electrolytes. Some ppl say they don’t need them, I know I did but had another re-adjustment around day 21 and needed very little after that. LISTEN TO YOUR BODY.
I started out planning on doing 21 days. Got to 21 and felt so good that at I thought 30… then 40… then settled on Easter as my end which was 55 days. I really didn’t want to stop, and had at least another 10 days of fat stores left to burn, but had to get back to work and other things.
I hope you find, as I did, that you have tons of energy and mental clarity through the roof. I’ve had depression for 2 decades and around one week into the fast it was GONE. I got more done during the 55 days of the fast then I had in the 55 weeks prior.
A completely unexpected side effect!
All the best, be smart and be safe. My comments are in no way recommendations.