If, during your Refeed, you feel weaker than you are right now on the WF, then readjust your diet please.
After my 40-Day WF, i had to tread very gently, drinking only minimal amounts of mono fresh juices... anything more and I felt deathly weak and my heart pounded like it was going to burst.
So pay close attention, listen to your body and don't let your eyes get too big, appetite-wise.