Older bro addicted to food?

honestly there is nothing that you can really do, unfortunately its his choice. His gf cooking him healthy meals is a good start but you cant force him to lose you can just keep explaining to him that you dont want him to die and hope that it sticks. I mean you can find a specialist in the area that deals with food addiction (psychologist) and see what they suggest and if they will help him. But one thing to remember food addiction is like any other addiction he has to want to make it work in order for it to work, good luck.