If your weight loss has slowed or stalled, try looking at the Calorie Differential Over Time report. It may show that your daily calories have crept up, or that you've let the amount or intensity of exercise drop. Look at the Calorie Differential Report weekly numbers to follow the trends.
To access the report, go to "My Tools", then select "Reports". On the right hand side of the second row is "Calorie Differential Over Time". Note that the orange section, the Basal Metabolism Rate, is a function of your weight. As you lose weight, it will also fall.