Well, you have only beeen doing this for a week...and it takes a while to get results. You didn't get to 200 pounds in a week, and it isn't going to come off in a week either.
A healthy rate of weight loss can be 1/4 to 2 pounds per week. Usually quicker the first few pounds, and then slower afterwards. I recommend only weighing in once a week though, and at the same time of day (first thing in the am, etc.) When weight loss is going in 1/2 pounds increments and you weigh in too often-it is easy to get discouraged because you don't see the scale move.
Give it some time...