So recently I came across a quote saying: "Fill your stomach one third with food, one third with liquid and one third empty" (or something like that). I thought that made sense of how to eat per sitting but then the problem --- how big is my stomach & how do I know when I hit a third. Plus, I tend to eat too much & then feel disgustingly full afterwards (I think it is that whole thing about it taking longer for it to register you are full).
So I googled it & found out that an adult stomach is supposed to be about 1L (sorry don't know what that is in gallons) or 4 cups. Of course if you eat too much all the time you can stretch it out, but that's another issue.
The point of all this babble is that I have been trying to visualize 1L whenever I eat & try not to eat more than 1/3 - 1/2 of that. I haven't felt uncomfortably full since and I finally broke my 20lb plateau!!!!
I have also been trying to watch slim women when they eat to see what they do differently than me.