The short answer is no it won't help. Basically, your body dictates where you lose weight. So wearing something tight around them won't help you lose fat in the area.
Now a valid use for something like this? Muscle recovery. I've seen some research that says compression clothing can help speed recovery when worn during and possibly after workouts. So if you experience a lot of DOMS (delayed onset muscle soreness), then you might want to look for some compression clothing but I wouldn't recommend this.
You can't out-exercise poor eating habits.