Yes, it is normal. When I did the 2 week induction for Atkins with my dh, I was very tired and lacked strength. They say it will pass, but I had to add back in some carbs(i.e. banana) before I felt better. I still have no sugar or white flour products and eat cleaner now than I did before. I also lost 16.5 pounds in 17 days which was too much to lose in such a short period of time. If you keep it up your body will adjust and you should be fine.
Hope that helps you.:7