Not to worry! I would say hang in there and if by day 5 you are not feeling better then I would check into other reasons. I believe Dr. Atkins says in his book that if you are feeling very weak (like feeling as though you ran a marathon after climbing a few stairs) then you need to up your carbs for a few days and then go back to 20. I too felt horrible on days 3 and 4. Day 5 was when I started to feel better. Hang in there!