MrsB247 I feel your pain and anguish , as long as he’s still being nice and friendly to you I wouldn’t throw him out , It could make it worse. I would talk to him as an adult and tell him that you understand his choices ( make him feel like an adult) but he has to understand the home rules.
As others are working in the house he needs to come home at a decent time as so not to make noise.
Also take a photo or two of him without his top and mention to him that he’s loosing weight .
Involve him in family things get an connection going.