You need to get through to him that this is critical stuff. A stroke could = death! That's got to get the attention of anyone. There's no other way around it about exercising and eating right. Is it possible that he can join up with you at gym and you guys can help each other?

Also, on his BW, how's the hormone panel? Maybe a candidate for HRT? Actually, this would be a great place for him to visit and gather information. You got to be direct and straight about this with him, because if he takes it lightly he'll just blow it off ...