Does the mother have the right to stop her daughter fasting because of nutrition?

Praise be to Allah.

The parents have the right to prevent their child – be it a son or a daughter – from observing voluntary acts of worship, whether they are Hajj, fasting, jihad or others, especially if the parents think that doing this voluntary action will be harmful to the child, or if the parents have some need that cannot be met otherwise. But in the case of obligatory duties they have no such right. If the child is prevented by his parents from observing a voluntary act of worship, then Allaah will reward him.