I've just started my second Master-Cleanse on Saturday. I did a 12 dayer back in november, now I'm heading for the full 40 day(or maybe more if I feel necessary;)) And the cause: I've Hashimoto thyreoditis, this is an autoimmune form of hypothyroidism. I don't have energy but I do have brain fog(hate it, I had such an excellent memory before), bad mood and other minor stuff...