Definitely. My very first fast was 120 hours. I was only aiming for 72, but felt good, so I pushed it another day. The group I was in had something they called the “Century Club” for those that made it to 100+ hours. I wanted in, so I didn’t break at 96 being that close to 100. 100 would have been around 11pm for me, so I just went to bed. I woke up feeling ok the next morning. It got a little rough around lunch time, but held out until dinner.
Best of luck!
I think it would be more accurate to say that if you’ve done a few 72 hour fasts, then yes a 120hour fast would extremely possible. I only say this because I’ve done hundreds, have helped hundreds, it seems hours 40-75 are the most brutal. Regardless, you can do this if you simply choose to do so and make it happen!
My very first fast was 14 days, my only prep was research. I think it depends on your intention, state of mind and physical ability to do so (I don’t think anything more than 14 days would be physically healthy for me now unless I gain some weight first).