The Ketosis is a funny thing. Years ago I did a fasting for therapeutic reasons which got me into ketosis pretty fast. I only did it for a week ( of only water, can you believe it? ) but I remember so well the metallic taste and the horrible breath!
With Dukan, for some bizarre reason I did not feel any of those things, I was normally hungry ( not like I was during my fasting in which My hunger went away after day 3 completely )
Did I go into ketosis during Dukan? I don't know, I don't think so, but it might have been very mild in my case.