Sounds to me like he's trying his guts out but just doesn't know what end of the stick he's at. Given he doesn't appear to have a problem with gaining weight, he's probably never had to think about what is healthy, restrictions on calories etc. The more you include him in what you do the better. Just be sure you say "wow, that was really thoughtful, thanks so much, unfortunately I can't have any tonight because of X reason, so maybe I'll save mine for tomorrow and have a salad (or whatever) tonight" and then when you eat it tomorrow say "wow, that was really yummy, you'll have to tell me when you are going to buy them next so I can make sure I have room by dinner!". The old encouragement trick never goes astray.
As far as people telling you what you are doing to lose weight is wrong, sometimes I think people get so caught up in what works for them, they don't think about the fact that everyone is different. I don't count calories either, I just don't have the patience to add everything up in my head. I couldn't attend a gym if I tried. But for other people calorie counting and gyms are must haves. I always try to remember that when people ask me for advice and usually tell them to look for something that might work for them - think about what they enjoy or what problems they encounter and find ways to overcome them.
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"