Q: How much weight can you loose after purchasing a dress?
A: There is no one answer to this questions. Each person looses weight in a different way, effecting their bodies differently. Pounds are not the important number, inches are. Each change in size equals about 1 to 1.5 inches of change in your measurements. Ideally 1 dress size in change would be best, 2 at the most, which equates to 1 to 3 inches of change. Garments that are much too large often need to basically be taken apart and re-cut in order to hang properly on the body. This is such a labor-intensive process it can quickly get expensive. Most dresses have princess seams to allow this reconstruction to happen and things to remain symmetrical. When you take things in too much things become off center and the fit becomes different than what the original design intended.
Q: How much weight can you loose after the first fitting?
A: It's best not to loose more than 5-8 lbs after the first fitting. Your measurement inches will be minimally affected from that, but once you hit the double digits it can start to alter your measurements. Crash dieting is not advised, but continuing a healthy diet and exercise after the first fitting is fine.