So sorry about your knee. I love to exercise. it seems to complete me. I had to quit the treadmill for a few weeks due to hip pain. It's probably arthritis. I had an x-ray several years ago and it was starting then. I get into a mild depression when I can't exercise, causing me to eat more comfort foods. I started using the treadmill again yesterday and sure enough the hip pain came back. It's hard to lift the one leg when this happens. I'm afraid to get an x-ray now for fear of what I'll find out. Isn't that crazy?
My only advice to you would be, try not to think of it as dieting. If you stopped the treadmill you will simply have to eat less. This should keep you from gaining and will help with your weightloss.
Now, I need to follow this advice for myself.
Good luck to you..hope your knee gets better soon.