Started Primal three-weeks ago. I've lost 4 pounds and a belt loop. I wonder though if I should have lost more? I have my carbs within the right zone for weight loss. Is it possible, since I have been a carb-freak (pasta, bread, etc) for so long it may take a while for my system to adjust?
If you started three weeks ago, keep going and know that you are doing a good job! When people have taken the 30-day challenge, sometimes dramatic results occur near the end. Personally, I think dropping a belt notch is wonderful testimony.
Also, if you are exercising, keep in mind that body composition isn't always related to a scale weight number. I've been gaining weight with muscle (some gym and CrossFit), yet my pants size either stays the same or is getting looser. I now need a belt for my favorite pair of cargo shorts. Some friends of mine have also reminded me that there are periods when you don't appear to be dropping scale weight, but that the body is re-adjusting itself: your pants fit looser, your face becomes slimmer, etc.
You might also consider taking before/after photos and before/after body measurements. A great way to track yourself and your progress.