Most do. Most women are able to take off that weight with diet and exercise. You do have to make that effort though. It likely won't come off with just coming off of the Depo-Provera provera (medroxyprogesterone). Keep in mind it also won't come off in the first few weeks. A few women just can't seem to lose that weight, but that is rare.
I recently switched from Depo-Provera to mirena (levonorgestrel) due to extreme weight gain. When will I begin to lose the added Depo-Provera weight?
No magic. The weight you gain (not all women do) is "real" weight. It is not water weight and will not come off quickly. Luckily you will not experience this with Mirena (levonorgestrel) - a very good choice on your part. Dr. Oz (google on internet) has a very good two week weight loss diet that will get you started in the right direction. It's going to be diet and exercise, difficult kind of work, that will shed the lbs.