I used to believe that too. Just eat low caloric density foods, right? It makes a lot of sense. So, I calculated the precise caloric density of Everything and ate nothing but <0.8 calories/gram foods with increased emphesis on 0.2 I had to eat truely vast amounts of food to get anywhere near full. We're talking many many pounds of spinach and 8 zero calorie jellos, pound after pound of vegetables and high fiber fruits: like berries.
It does NOT work well at all. Don't get me wrong, it helps a little, but your stomach is extremely smart and it knows alot more about calorie counting than we do. Like it or not, it keeps it's own account of your calorie intake and adjusts your hunger and appetite accordingly.
If you're like me and you're already eating a very healthy diet and you exercise regularly and your still gaining weight, you only have one option: go hungry. Very hungry. Right now, it's the only way. You could exercise a lot more, but either way, you're going to suffer.