There is both science and psychology behind it. First, it challenges your digestive system, as long as it’s something you don’t otherwise have issues with. 2nd, it puts these foods in a proper place, something to be enjoyed occasionally, a reward, a treat.
Where I used to eat a whole pizza by myself, and would do it whenever I wanted, now it’s a slice or two, once every couple of weeks. I apply this to fried rice and my all time favorite, pasta. One meal, sensible portion. Enjoyed and savored because I earned it. Not enough to crash my diet or throw off my blood sugar.