one's normal blood sugar levels prior to the fast can have something to do with how you feel in the beginning. whenever i fasted after a low blood sugar diet the conversion to ketosis was not as dramatic, the system was already used to low glucose. not recommending it of cause, just my thing.
iron stores may take a while to transfer, pH changes can cause major fatigue (google 'pH neurotransmitters') causing slight paranoia, sleeplessness, even nightmares in the first few days (goes quick thank goodness)
Thank you for your input, no wonder why this message has been recommended by a moderator. I did indulge on way too much sugar prior to this fast and I am sure that 's the reason why i felt such unusual weakness! By slight paranoia do you mean the weird ideas you can get when you fast like: "what if there is a food shortage, maybe I should stop my fast and eat now!" LOL.