>>44037 (OP)I am not a doctor but I've been doing belly stuff for years and here's what worked for me.
Feeling full happens when your stomach has no more room for food. Hunger is a thing your brain does when you don't have enough calories. Eating when you aren't hungry is what makes bags of potato chips disappear. Eating when you're full because your cells need it is what makes bellies able to stretch further than usual.
If you want to increase your gf's stomach capacity (for feederism/enemas/air inflation/whatever), she needs to eat over 2 pounds of food (the most a normal stomach can hold) before she eats as 2000 calories (the energy the average woman burns by existing). You still want her to eat 2000 calories, but she needs to feel full before she stops feeling hungry. So fruit, yogurt, pudding, jello, things like that. Healthy snacks.
For me, I started by adding 2 pounds of pudding/yogurt/jello to every meal. For the rest I ate 4-5 pounds of pizza, burgers, junk food. Counting for drinks and candy, I went from eating 5 pounds a day to 10 pounds a day.
Once I got used to that I started adding other stuff like pints of strawberries, drinking more water, a watermelon or two when we can get them. On average I eat 30-40 lbs. a day, but since a lot of it holds little nutritional value I don't gain a lot of weight.
(That's 30-40 lbs. coming out the other end though, so... something to consider).
That all being said, my doctor doesn't care that I want a huge belly. My doctor cares about me being healthy, my partner cares about me being healthy, and 9 out of 10 doctors recommend being healthy.
So talk to with your partner and more importantly talk to a doctor, ya dingus.