Dietary fat is the fat that is found in food.
Dietary fat is found in most animal foods such as meat and dairy products and in oils, salad dressings, and mayonnaise. Bakery products, fried foods, some gravies and sauces, and most highly processed foods also contain fat. Fat takes longer to leave the stomach than either carbohydrate or protein, so a person feels fuller for a longer period of time after eating fat.
The body uses fat as an energy source. Any extra dietary fat is converted to body fat and stored in fat cells. The human body has a nearly unlimited capacity to store fat. The body can use these fat stores later for energy.
Fat is necessary for the transportation and absorption of fat-soluble vitamins. These vitamins are A, D, E, and K.
Fat also helps to cushion the body's organs and to maintain the body's temperature.
Lowering saturated and trans fats in the diet can help prevent obesity, heart disease, and some kinds of cancer. The National Heart, Lung, and Blood Institute, NHLBI, recommends a total fat intake of between 25% and 35% of total calories each day.
Fats and oils are made up of basic units called fatty acids. Each type of fat or oil is a mixture of different fatty acids. Most of the fat in a person's diet should come primarily from fats that contain mostly unsaturated fatty acids.
These foods can be from both plant and animal sources. They are usually liquid at room temperature.
Unsaturated fatty acids include monounsaturated and polyunsaturated fatty acids. Fats that are mostly monounsaturated are canola, olive, and peanut oils.Fats that are mostly polyunsaturated are safflower, corn, and sunflower oils, soybeans, many nuts and seeds, and seafood.
Replacing saturated fats with unsaturated fats in the diet has been shown to help lower blood cholesterol levels. NHLBI recommends that up to 15% of total daily calories should be monounsaturated fat. Up to 10% of total daily calories should be polyunsaturated fat.
The American Heart Association recommends a diet low in fat eith saturated fat providing less that 7% of daily calories.
An important polyunsaturated fat is omega-3 fatty acid, which comes mostly from fish sources. Omega-3 is an essential fat, which means that the body can't make it. It must be derived from foods.
Some studies suggest that omega-3 may help lower the risk for heart disease and heart attacks.
Saturated fats are considered bad fats. They come mostly from animal foods and are usually solid at room temperature. The only plant sources of saturated fats are oils made from coconut and palm. Eating a lot of saturated fat may raise the carriers of bad cholesterol in the blood. These bad carriers are called low-density lipoproteins, or LDL. A high amount of LDL in the blood can lead to plaque buildup in the arteries. This can cause atherosclerosis.
Having high cholesterol levels in the blood is a major risk factor for heart disease.
Another type of fat is trans fats. These fats are formed when vegetable oils are processed into margarine or shortening through a process called hydrogenation. Sources of trans fats in the diet include snack foods and baked goods made with partially hydrogenated vegetable oil or vegetable shortening. Trans fatty acids also occur naturally in some animal products such as dairy products.
Trans fats raise LDL cholesterol levels and may also lower HDL cholesterol in the blood. They also raise total blood cholesterol levels but not as much as more saturated fatty acids. It's not clear if trans fats that occur naturally have the same effect on cholesterol and heart disease as those produced by hydrogenation of vegetable oils.
To limit the amount of trans fats in the diet, the American Heart Association (AHA) recommends using a margarine with liquid vegetable oil as the first ingredient and no more than 2 grams of saturated fat per tablespoon.
Daily intake of fats and oils should be limited to no more than 5 to 8 teaspoons. This means that these foods should be used sparingly for a healthy diet. Following a diet that is extremely low in fat can cause vitamin and mineral deficiencies. However, most people would find it very difficult to limit their fat intake severely enough to cause these deficiencies.
It is important to include unsaturated fat in the daily diet. Reading food labels is a good way to identify foods that are high in fat. All food labels are required to list the grams of total fat and saturated fat.
A food with 3 grams or less of saturated fat per serving is considered a low-saturated fat food.
Be aware that just because a food is fat free doesn't mean it's calorie free! Many foods that are low in fat contain high levels of sugar and calories per serving.
Tips for lowering fat intake include: adding fish to the dietchoosing low-fat or fat-free (skim) dairy productseating leaner cuts of meateating a meatless meal at least once a weekremoving skin from poultry before eatingtrimming off visible fat before cooking meat
The American Dietetic Association's Complete Food&Nutrition Guide, 1996, Duyff.
Food, Nutrition&Diet Therapy, 1984, Krause and Mahan.
A Low-Fat Eating Plan: Favorable Tool in Blood Cholesterol Control, but Not a Panacea for Everyone, 1996, American Dietetic Association.
Project Lean Low-Fat Eating for America Now, 1995, American Dietetic Association.
The Details: Fat&Fatty Acids, 2000, American Heart Association. [hyperLink url="http://www.deliciousdecisions.org/ee/wbd_acids_main.html" linkTitle="#xA;www.deliciousdecisions.org/ee/wbd_acids_main.html"] www.deliciousdecisions.org/ee/wbd_acids_main.html[/hyperLink]