I've never broken any of my broodies because I don't see the point in fighting nature. They'll only go broody again when the fancy takes them. I just let them sit for the 6-7 weeks it takes them to realise no babies are coming, and then that's it. They molt, and start to lay again.
One of our Orpingtons in her youth was a persistent broody. She would lay 10 eggs and go broody, again and again and again, all spring, summer and autumn (but then she'd lay all winter for me). She's still happy and healthy today at 6 years old but a lot less broody these days.
From the reading I have done, especially in the Meat birds forum, broodies lay down a huge amount of fat predominantly in their pelvic area before they start to sit and that sustains them, even though they may seem to be losing weight.
Being a broody breed Shadow is going to want to be broody so you really are fighting a losing battle. You might break her but it won't be long before she wants to sit again. I'd be getting her some sexed chicks to raise (which you can then sell as pullets) as that at least would break her and extend the time before she wants to go broody again. Or move her inside if you are worried about the day time temperatures where you can monitor her food and water intake, and let her sit it out. Then she'll molt and put on condition again for around 6 weeks before starting to lay again. That too would extend the time before she goes broody once more (and she will).