Fitness experts! Help me with this one!!?

[nikki w]

The day after I came home from the hospital after having my third child, I weighed 191 lbs. I went shopping probably a couple weeks later and could not squeeze myself into a size 17 pants. 19s MIGHT have fit, but I can't even promise that one. 15 months later I wear a size 9 or 11 and I weigh 180 lbs (I'm 5'5"). What gives? I do go to the gym 4 times a week and do 45 minutes to an hour of cardio. In the past for me, one pant size equaled out to 10 pounds lost. Well, I have lost 11 pounds and 5 pant sizes. I am not complaining about the size loss, I just can't explain the lack of weight loss.

[Mary]

muscle weighs more than fat. Basically, you turned your fat into muscle, which is awsome! When you have muscle, your stomach maybe flat. but you could still be heavier. This is normal, good job on the pant size loss, your doing great!