I actually hear "living in your body" fairly often in eating disorder recovery. I don't think they use it the same as an obeast does. It's supposed to mean being 'present' in your body, i.e. actually paying attention to hunger signals or what your ED voice is telling you to do and how that confirms/conflicts with what your body is telling you. Not really the same, so it seems like yet another thing hamhands have warped for their own use.