I agree with you. When you look on a 1200 calories diet food list you can't believe people can feel full after eating it. I think after you're already sometime on a diet, your stomach is getting used to less. I think it has to do with how and what you eat. Drink water.Drinking a lot of water reduces the hunger and helps your body to burn fat. Eat slowly. Very slow. You start feeling full after about 20 minutes of eating. Here's an article about weight loss foods:
http://www.burnthefat.com/list-of-top-10-weight-loss-
foods.html