Over time your sleeve will heal and you will gradually be able to eat more. If you are constantly overeating through the process then it will expand more then it would have on its own. It will though never have the capacity it did pre-op as the fundus which is the part of the stomach that stretches never grows back. I had a plication so similarly the fundus is sealed off and will never be accessible to food again. The short answer, yes you can somewhat stretch your sleeve. I would imagine though the throwing up from constantly overeating would be the worst side effect of that process.