For all of the low-fat rhetoric, know this: Without fat in our food, we might as well be eating cardboard. Not only do our bodies need fat to function, but the simple fact is that fat tastes good. It may also trigger chemical receptors in our body that create a feeling of fullness and well-being.
So fat isn't all bad. Actually, some types of fat are downright good for your arteries. Get enough of these "good" fats, eliminate enough of the "bad" fats, and watch your cholesterol levels improve and your heart disease risk plummet. This doesn't mean you have free rein when it comes to fat; we still want you to limit your overall intake of fat to about 25 percent of calories. The point is that both quality and quantity count. Take the time to learn about both the good and the bad fats so you can choose foods effectively.
When you think of fatty foods what do you think of? Butter. Milk. Steak. Hamburgers. Cream. Cheese. You can just taste their richness now, can't you? Well, much of that richness comes from the high level of saturated fats in these foods. Saturated fat is solid at room temperature -- picture the congealed grease in the pan after you fry hamburgers.
http://www.rd.com/living-healthy/get-savvy-about-fat/article16071.html