I agree it can be psycological in some ways. For me a large salad with chicken breast is much more filling then a hamburger, though the hamburger has alot more fat and calories. Some of it is the fiber, but most of it is the amount of food. For me I like to have a larger meal with lots of bites. I think that's why I never liked the mock danishes, there just didn't seem to be much there. However a huge plate of fried cabbage with my eggs, or zucchini hashbrowns are filling.

However with these meals, even when I was having 4-5 meals a day, I wasn't breaking 1,000 calories. For me oils were the way to get in calories and fat (I rarely eat red meat due to cost). If you just add more calories on top of what your having, then sometimes there can be problems. If you are eating too little, or if you are having too much protien, changing the ratio of fat in your existing calories can help.