What strikes me as odd about this proposal is that the proponents want to take the child out temporarily and return the child once they feel it's safe. Well, the only way they are going to make it safe is to work with the family and teach good practices, and since they are going to have to do that anyway, why take the child out? We are not taking about an abuse situation where the child could be killed at any moment. Obesity is a long-term problem, so there's no real urgency to take the kid out.
The proponents also want to reserve this for only extreme cases, but when we try to implement these kinds of policies and limit them to only the appropriate cases, it just doesn't work out. We know that decisions are sometimes made in arbitrary ways, and there are often racial and socioeconomic undertones. So removal from the home may not be done in a fair way.