Well I can't answer your question directly, but can share my experience with my first (20 day) MC. I just finished Monday and am on day 3 of my break. I *already have* low T3 and have been on thyroid glandular (and adrenal, have severe adrenal fatigue as well) since March. I was VERY worried about going off both meds, as I have zero energy and need 12 hours sleep a day when not on them. Thyroid in particular, because I ran out for a week before sourcing it again, and even though I was still taking the adrenal glandular plus mega B complex, I crashed big-time and was exhausted until 4-5 day back on it. So needless to say I did not want to go there again.
But was informed here on curezone on the juice fasting forum (which I started with for 4-5 days) that I should drop the meds and let my body heal and do what it needed to do. My energy was GREAT except for day 6-7, and the first few days after starting Oxypowder
on day 15th, which released a LOT of toxins. I couldn't be more pleased, and am hoping against hope that now I'm breaking the fast my thyroid and adrenals continue to remain balanced, as they apparently are. Would be nice if the metabolism was also reset and I continued to drop the weight. Lost 14 lbs in all. So fasting with the Master-Cleanse
has so far HELPED, not hindered my thyroid. Though can't say that would be the case for everyone...