It's perfectly natural to slow down or stop in week 3, it's not a stall. Most of the weight lost the first week of induction is water weight. The second week you start to lose fat. After such a sudden weight loss, your body takes a momentary pause to make sure you are going to keep this up and that the fat is still going to be coming in. The weight loss will start back up again if you continue following the plan. It will be much slower though as it is fat that is being lost. That's normal. Atkins is not a quick weight loss crash diet, but a way of eating for life.

The general rule I've seen stated on here is most people lose 10% of the weight they need to in the first month and 5% each month after.