>The farthest I’ve been able to go is 3 day fasts. The massive headaches always bring me out of it.
Yeah, I’m type one so I have to be careful of my blood sugars as well, because your liver dumps all the sugar it has for two days and then runs out. That might be the headache reason.
I would advise working your way up to multi-day fasts. Start out doing 16-8, or 20-4 intermittent fasting for a period before trying to go longer.