I had no loss in the third week either. I just lost a half a pound today in my fourth week. Boy did I cheer when I saw that little 1/2 pound loss on the scale this a.m.
I think our bodies need to adjust and regroup before they will let go of some more weight.
I learned a few great tips from these forums.
1. Do you feel better? -- Then its working.
2. Is your skin clearer? -- Then its working.
3. Are your clothes bigger on you since your started? -- Then its working. (Take your measurements too, I just did. It will help keep you motivated when your body readjusts itself without showing you a loss on the scale.)
4. You are in ketosis? -- If so, you will lose eventually. Reread the Dr. Atkins book (I am on my third read and learn something new every time I read it.)
5. If you are exercising, you are building muscle which weighs more than fat so you may actually gain before you lose, but you will lose. (Read these fourms everyday and view other people's profiles and that will motiviate you. Their journals are great!)
6. Keep a positive attitude and don't give up. If you were a slow loser before on previous diets then you most likely will be this way too.
7. Drink more water than you think you need.
I too got really excited with the initial loss and then a little depressed when nothing the third week (even with working out 5 days a week.) Stay positive! We all know we didn't gain it over night. Oh yeah, don't cheat!
Way to go on the loss, stick to it, it works!!