I sometimes advice taking calcium supplements (almost with vitamins) to those who are on intense dieting for weight loss usually.
Calcium have many roles in body. The role of calcium specific to weight management is very important too.
Calcium levels in blood is one of the few most important factors which help the body to decide if it is in starvation mode or normal one.
Like, if you take very low calories per day, your body will put on the reserve mode or starvation mode to preserve the energy. But if your body have sufficient calcium in blood, it will think it as something else, so your body MIGHT not move on to starvation mode (might not because calcium is one of the factor, not the only one).
But calcium unnecessarily supplemented is not recommended. It may lead to long term affects including affect to heart muscles too. So don’t use it unless you are sure what you are doing, and don’t go above recommended dose. You can also take it irregularly or on alternate days.
One more important thing is to not to take calcium with meal or with iron tablets, because it interferes with the absorption of iron, which is again very important for body.