The first step is to stop focusing on the bathroom scale. Often a change in the scale reflects the pounds of body fluid you lose and gain every day rather than how much fat you've lost or gained. Also, because muscle weighs more than fat, you can lose inches of fat without losing weight.
Many experts recommend a measuring tape or a tight pair of jeans.
But don't go to extremes. Don't keep trying on those jeans or measuring yourself every week. Instead, check your progress once every four weeks and chart the results. This will give you a better idea of how you're doing, and will help keep you from getting frustrated at not seeing dramatic weekly improvements. In order to lose one pound of fat, you must burn about 3,500 calories.