Hi - I can understand the back injury thing, having skeletal problems myself. If you can walk around the house, there are ways that you can get exercise that doesn't strain the back. I get the bulk of mine by putting my groceries and laundry away one at a time. The beauty of this is that if I get tired, or my back or hips start to suffer, then I can easily stop and sit. another beauty of this is that I can save it for when I feel like doing it - except I don't leave the fridge stuff for another time. If you can do this, then that can distract you for a while.
You can get onto SP and check out the various articles and message boards. I actually used to get so lost in them that I often forgot about my meals until I suddenly realized what the time was.
If you find the craving for sugar too much, then it wouldn't hurt to have some dried fruit on hand - things like figs or dates. One or two of them are far better for you than processed sugar. You get other nutrients and fibre as well.
Below is a link that you may find helpful if these tips don't work: www.sparkpeople.com/resource/nutrition_art
Good luck :-)