I felt tired, foggy, and achey for the first 4 days as well. I didn't really feel hungry, but I was very preoccupied with food. I turned a corner on Day 5 and felt much better-- and since then it's been all good. I am on Day 13, hoping to go to 21. Just take it a day at a time-- you'll likely start feeling better very soon.
Good luck to all of us!
PS-- Make sure you're drinking a minimum of 6 glasses of lemonade every day, along with plenty of water!