StoryEnjoyer:
I wonder if keeping your stomach stretched and bloated with like, soda water would work. Zero or low calorie.
If this is a question of how to keep the capacity.
Increasing or maintaining your capacity is a terrible idea if you are trying to lose or maintain weight. It will only increase your hunger and undo your progress.
If you are committed to maintaining or losing weight, you'll have to make your peace with reduced capacity.
Can you keep your stomach constantly stretched with liquid bloats? Yes. But even then, I do not recommend it. It will do a number on your kidneys. This is on top of certain liquids throwing off your electrolytes and other nutrients your body needs from over-hydration.
Any regular bloater will tell you that you have to be mindful of your liquid intake. Doing otherwise can lead to painful leg cramps, blood sugar spikes, water toxicity, and other symptoms, depending on the liquid you're bloating with.