I've heard people doing it both ways - stopping the meds and fasting and slowly weaning off of it.
Once I hit 75% raw, my body started to heal - blood pressure came down, weight came down and I had my thyroid tests done and both my T4 and T3 were super high, so my doctor cut my Armour Thyroid back (Armour had T4 & T3). I'm sort of stuck now. Weight is the same (a few pounds back on), my blood pressure teeters between normal and a little high. So I figure my blood work won't show any difference. So I did a modified Master-Cleanse for about 10 days (modified because each day I seemed to have to sneak at least 1 food in a day), so now I'm going to try to do the real thing now, in hopes that I can go in and have my thyroid meds reduced some more and that my blood pressure will stay normal. I only have about 2-3 weeks of meds left, so I'm hoping with doing the Master-Cleanse faithfully (with no cheating), my bloodwork will show I need a cut back in 2-3 weeks.