On the other hand, there certainly have been cases where social services have removed children from parents where children have become obese, and the parents have been taken to be at fault.It seems to me to be an issue that needs to be considered on a case by case manner. There may be something in the parents' behavior that encourages obesity in the children, in just the same way that a parent may be in trouble with the authorities for letting their child play by a road.
We tend to think that although many parents are not ideal, it is generally better for children to be brought up by them than by removing them and trying out alternative carers for them. There are clearly cases though where parents do not take account sufficiently of the dangerous situations in which they place their children and intervention by the state is then justifiable. Obesity could well be such a situation, especially given the wide range of ailments to which it leads.