I agree with a lot Kate has said. As hard as it may be for you, all the good intentions in the world will not make him do anything he doesn't want to. My advice is to just let him know that you are concerned for his health. Try not to harp on about it or tell him every latest thing you have heard of that could help him, but if he asks for help/support, try to provide what he asks for (e.g. if he asks you what did you change in your diet, tell him that).
It's hard when you first start to make changes in yourself to see others in similar situations - you just want to make them change too and do all the things you did that worked for you, but sometimes it can do more harm than good. When I first started getting good results I just wanted to tell all my friends who made the mistake of saying "i wish I could get the same results" what they should be doing, in detail. I quicky learned that it wasn't appreciated, so I just give the advice they need and no more, such as "well, I'm sure you can get the same results if you find something that works for you, if you want any support, I'd be happy to help" - that way they know they can do it and that I am supporting them and if they want to know what I did they will ask. Also, what works for one person may not work for another.
35kg lost. (November 2005 - October 2006)
15kg gained again (as at October 2010).
Back to the drawing board - Let's do this thing!
"You can't change the winds, but you can change the sails"
"Reach out and take control of what lands in your lap"