I agree with Mr. Weapon. Can she walk or is she bed-bound? If she is restricted to her bed is this because of being obese or from another disability?
She needs a steady stream of nutrients and glucose primarly. She is retaining all of that fat because she is only eating once per day. Her body does not know when it will get fed again so it
retains all of that fat. She basically needs to get on bb diet with less calories. I would have her see a dietitian or a dietitian see her, whatever as long as a professional can assess her dietary needs and help her. This might have to do with her self image too, and not wanting to go outside. Find simple things she enjoys and do that with her. Hope this helps!