I like adding things to my icecream, usually peanut butter and frozen fruit. Got to thinking that if I added oats I could actually increase the volume without impacting the flavour all that much (I like oats). I could probably use floured starches or something like that.
Are there other things you “fill”? I think juice + water is the most familiar example. What about something like adding 20% dehydrated milk to fresh milk? Substituting some butter for oil?
Sometimes I find when I’m making my own stuff it ends up being more expensive than buying the packaged variety from the store, but maybe fillers are a way to balance that out.
The most historical filler is starches to stretch a protein. A smaller serving of meat goes a long way when served with rice, pasta, potatoes, etc.
Consider how to fill a meal as well as individual ingredients.
Iake.my own almond milk. I save the part left behind after squeezing out the liquid. Lay it out on a tray and let it dry, send it through a blender till fine. Free almond flour! I add it to my pancake mixes and baked goods for extra protein and so I don’t use so much regular flour (or pancake mix).
Foods with more water in them are more filling. Grapes fill you more than raisins; soup more than a roast.
Fiber (and fat) also makes you feel more sated; I always load a sandwich or taco up with greens for that reason.
Dried foods are the best value, I would experiment with that. Rice is famously filling and cheap
I add frozen vegetables to a lot of things to bulk it out. Some examples include frozen spinach to pasta sauce or frozen broccoli to Rice-a-Roni-type meals.
If you have access to a friendly butcher or Asian market, fat, lard is a excellent way to make tasiter and more filling meals. You can add it to most dishes as a enhancer.
But unless your doing keto/carnivore you probably want to moderate your fat intake
