I experienced that because I upped my dose too fast.
He says if you start feeling lame to back it off a little and take your time. All that crap didn't get built up in you over night and it'll take a while--your body can only eliminate so many toxins at once...
I personally think it's easier to progress through the diet backwards--going from the least to the most restrictive phases.
My roommates aren't even on the diet yet but they experienced detox symptoms just from switching to organic products!
Keep it up though, you're going to feel the best you EVER have soon! :)