First, a stall is technically more than six weeks with no weight loss and no inches lost. Most people experience plateaus, where you won't lose for a week or longer. It's generally thought that the body is readjusting itself during these times to the changes in body composition.

You can loose inches but not pounds because you can gain muscle at the same time you loose fat. A pound of muscle is much more compact than a pound of fat, so you'll loose inches, but might not loose weight - or even gain weight, in some cases.

As far as hypo and hyperthyroid go, which symptoms are you experiencing?