I know it is very tempting to think so, but the answer is not a simple yes or no.
It can help in some cases and harm in others. Like any other drug, and I'm talking about medicinal drugs here, it should only be taken when the benefits out weights the potential harmful effects.

There are many scientific studies that show potential benefits of taking cannabinoids, but so many others showing the opposite.

I would like to point out a very well known drug among those that study this subject, rimonabant. It interfered with the activation of one of the receptors and was used to decreased appetite and help with weight loss. It was thought to be safe, and it was very effective. Some time after its commercial release it was noticed that many people using this drug ended up committing suicide. It was later figured out that the reason this drug was so good at decreasing appetite was that it blocked the "feeling of pleasure" in the brain. So sure, people stopped eating, but became seriously depressed to the point of ending their lives.