The sleeve works by giving you restriction, so you eat less and lose weight. The restriction gradually lessens as time goes on, so while you have this benefit, it's crucial to develop the right diet so you don't regain the weight you have worked so hard to lose.
It's unfortunate that you aren't able to exercise, but that's really not the key to maintaining your weight loss. The amount of calories you could burn with exercise is easily countered by one helping of high calorie food. Sure, exercise would help but it's really the food restriction that creates the weight loss.
Depending on the nature of your disability, it might be possible to do at least some form of exercise, such as sit and be fit, or some other program that could be tailored to your abilities. Again, it's not going to keep the weight off, but it can be beneficial to your health in other ways.
