My husband is disabled, and needs to lose weight, what can he do?

My husband was shot in Iraq Dec 26, 2007. He has little to no use of his left arm and leg. He can walk, but painfully. His left leg is actually 2 inches shorter than his right. He has a metal rod in his arm and leg. due to the pain medicine (narcotics and such), he gained 120 pounds. He now weighs 345 pounds. I am very concerned about his weight as he is only 5'9". He is still in pain, what can I do to help him lose weight without rigorus excercise. Any suggestions would be greatly appreciated.