. Helping the body to produce prostaglandins, which are hormone-like chemicals that regulate blood pressure, heart rate, blood vessel constriction, blood clotting, and the nervous system

. Allowing the fat-soluble vitamins A, D, E, and K to be absorbed by the cells of our bodies

. Helping maintain healthy hair and skin

. Insulating the body and protecting organs

. Providing the pleasant mouth-feel of food and the sense of fullness after meals

Scientists have even determined that simply eating fat doesn't make a person fatter. It's true that since fatty foods taste good and are dense with calories, it can be easy to overeat them. But as long as you don't take in more calories than you use, what matters about fat is the kind of fat you eat. Here are the four kinds of fat:

. Trans fat

. Saturated fat

. Monounsaturated fat

. Polyunsaturated fat

Trans Fats

These fats have been in the news lately because the Department of Health and Human Safety recently announced that, starting in 2006, food product labels will have to include the amount of trans fats that the product contains. Labels already include information about saturated fat, and with the addition of information about trans fats, consumers will be able to make better choices. Like saturated fat, trans fats raise low-density lipoproteins (LDLs, the "bad" cholesterol) in the bloodstream. Even worse, trans fats lower high-density lipoproteins (HDLs, the "good" cholesterol), which is needed to help the body eliminate LDLs.

Trans fats are human-made, created by adding hydrogen to vegetable oil. They are typically solid at room temperature, and you can find them in most margarines, particularly stick margarine, vegetable shortenings, commercial baked goods, like doughnuts, crackers, and cookies, and commercially fried foods, like french fries. Some newer home baking products have packages that say the product has no trans fat. Make sure you read the label, though, because you may find that these products contain a significant amount of saturated fat instead.

Saturated Fats

Saturated fats, like trans fats, are also solid at room temperature. When eaten, they can play a significant role in raising overall cholesterol because they raise both HDLs and LDLs.

Saturated fats come mostly from animal and dairy products like meat and poultry, butter, cheese, whole milk, cream, egg yolks, and lard. You can also find saturated fats in chocolate, coconut and coconut oil, palm oil, palm kernel oil, and many commercial food products.

Monounsaturated Fats

Monounsaturated fats are liquid at room temperature, but may solidify somewhat if stored in a refrigerator. According to the Harvard School of Public Health, monounsaturated fats can help lower LDLs and raise HDLs when eaten in place of carbohydrates.

You can find monounsaturated fats in olives and olive oil, canola oil, avocados, nuts, and peanut oil. If you use these fats in place of trans and saturated fats, you can lower risk of heart disease by reducing cholesterol. Monounsaturated fats also have some antioxidant properties, helping the body resist cell and tissue damage caused by oxidation.

Polyunsaturated Fats

Polyunsaturated fats are liquid at room temperatures and when refrigerated. Like monounsaturated fats, polyunsaturated fats can help lower LDLs and raise HDLs when eaten in place of carbohydrates.

These fats can be found in liquid vegetable oils, like safflower, corn, sunflower, soy, and cottonseed oils, soybeans, and flaxseeds. They can also be found in fatty cold-water fish, like salmon, herring, and mackerel. These fish contains a particular kind of polyunsaturated fat called omega 3 fatty acids. Omega 3 fatty acids help decrease the risk of heart attack, protect against irregular heartbeat, and lower blood pressure.

A Word About Fats and Cholesterol

Dietary fats are not the only contributor to high cholesterol. Smoking, lack of exercise, and heredity also have significant effects on blood cholesterol levels. Because of this, people need to make individual determinations about how to manage the fats in their diets.

Cooking Suggestions

It can be a rewarding challenge to change cooking and eating habits, and here are some suggestions. Afterward, you'll find a couple of recipes to get you started.

. Saute with olive oil or canola oil instead of butter or shortening. Light olive oils have a mild flavor.

. Use olive oil in salad dressings and marinades.

. Use canola oil in baking or experiment with substituting applesauce or prune puree for half the fat in baked recipes.

. Substitute slices of avocado for cheese on sandwiches.

. Choose peanut butters that contain only peanuts and peanut oil.

. Eat fish instead of meat several times a week.

. Snack on a small amount of nuts instead of commercially made chips or crackers.