This exercise works the oblique muscles.
Lie down on your side on a Roman chair or a hyperextension machine so that only your hip is on the bench and the body is hanging.
Place your ankles under the rollers.
Keep yout body straight, and your keep your hands behind your head or crossed on the chest.
As you inhale, slowly put down your body by bending at your side.
As you exhale, return to the starting position.
The exercise doesn't help to burn fat in this area. It involves the back muscles which can lead to your waist expanding.
If this exercise seems too easy, you can take a barbell plate.