Dinky (that's the I'm going to call you from now on because you're going to be think he pretty soon), you did not lose 17 lb of water. You lost a few pounds of water and a hold bunch of fat waste, which is the liquid by product of fat melting. Some people described it as ashes in some kind of fluid. But believe me, you weren't peeing protein and you can't possibly have drunk enough water to pee out 17 lb of it. Now our dear resident RN may want to correct me and that is fine if she does. This is just country wisdom that I have had since I began researching my diet and state of health.
Yes it is normal, but it is also normal to stop and slow down without even trying. Your biggest weight loss will always come at the beginning of a drastic change in diet. After that it slows down and sometimes it stops for a while. Enjoy it while you can because you are not going to lose 17 more pounds in another week or so.