I agree that weight reduction is more about the food you put into your body and less about the exercise, BUT.... I find that when I start exercising more, my eating habits improve. After putting in the effort for the exercise, I have no desire to undo all that good by eating something bad, so they go hand-in-hand in improving your attitude and your goal to get more fit. I think you'll find that even if you exercise a little bit, you'll be less likely to eat poorly - it's about the entire attitude of getting more healthy.
Sue