Working out builds up muscle mass. Muscle weighs more than fat. So relying on the scale leads a lot of people to believe they haven't made any progress--when in fact they have.

How are your clothes fitting? Does your body look and feel different? You might want to rely on what a a tape measure says, rather than a scale.

Which diet are you on? Atkins? South beach? Something else?

How much weight are you trying to lose? How many calories are you eating per day? If you cut back too severely, your body can go into "starvation mode" and resist burning its fat stores.

I've honestly never seen diet pills work well, so I can't recommend them at all. But with a bit more information, maybe I can help you figure out why you're stuck...