Just a suggestion, but if you can afford it, maybe you can hire a personal trainer for a few sessions to get your dh set up with an eating and exercise plan that will work for him? Or check out a book that has some eating/exercise routines. These are a few I have used and liked:
Body for Life is amazing and only requires about 5 hours exercise per week.
TNT Diet is another good one, and the exercise is about the same.
New Rules of Lifting is another one my dh and I have used.