Unfortunately, many people have the misconception that holding hand weights and doing side bending exercises will trim or tone the "love handles." However, this movement (lateral flexion) is performed mainly with the deep muscles of the spine and not the internal obliques
or the external obliques
. Instead, the quadratus lumborum muscle, which attaches from the iliac crest
to the lumbar vertebrae and to the lowest rib, is actually a primary lateral flexor muscle. What this exercise is good for is increasing lateral range of motion in the spine. If you do side bending exercises, make sure they are slow and controlled movements.