If you’re looking to reduce your sides, then no, this is a useless exercise. As Janet pointed out, you can’t spot reduce. Remember: you’re toning & building muscles with weights – not reducing their size. But even if you were looking to build those muscles, I would go with trunk rotational exercises vs. side bends.
I would ask your rationale for this exercise. Most people do it to try to reduce “love handles”, but you cannot spot reduce. It is also not a very effective exercise as gravity is doing most of the work, even if you hold weights. It you are trying to strengthen the obliques I would suggest using a resistance band for this motion. You should also be aware that spinal flexion is not recommended for those with osteoporosis.