So far I've lost about 43 lbs and I'm down only two pants sizes and one shirt size. I was a tight 16 (looser 18) and now I'm a 12. However, I'm a bit chesty and have a straighter body shape, so that may have factored in.
I'm really hoping the sizes drop faster the lower I go. We'll see.
I'm a student and can't afford to buy a lot of new clothes, so I usually wait until the things are falling off of me. I wore my 16 jeans until the fabric was literally folded over itself under the belt I used to strap them on. Then I broke down and bought a new pair. My shirts are still okay, though. I'm not sure whether to be glad or not.