dietary fatAlternative Names
fat, fatty acids
Dietary fat is the fat that is found in food. Fat is one of three main nutrients in food. The other two are carbohydrate and protein. There are three types of natural fats found in foods. These are mono-unsaturated, polyunsaturated, and saturated fats. Most foods contain all three fats in different amounts. The body can use all three types of fat.
Dietary fats have very important functions in the body. Only a moderate amount of fat is needed for best health. Too much fat or the wrong type of fat could be harmful. A good diet should have more unsaturated fats than saturated fats.
Fat is a concentrated source of kilojoules. It provides 37 kilojoules per gram of fat. Carbohydrate and protein provide 16-17 kilojoules per gram. So any type of fat should be used sparingly in the diet.
What food source is the nutrient found in?
Dietary fats are found in most animal foods, such as meat and dairy products, oils, salad dressings, and mayonnaise. Bakery products, fried foods, some gravies and sauces, and many other foods also contain fats. Fat takes longer to leave the stomach than either carbohydrate or protein, so a person feels fuller for a longer period of time.
How does the nutrient affect the body?
The body uses fat as an energy source. Any extra fat is stored mostly in the body's fat cells. The body can then use these fat stores for an added energy supply.
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 temperature.
Lowering fat in the diet to recommended amounts, can help prevent obesity, heart disease, and some kinds of cancer. This is especially true for saturated fats. The Australian government recommends a total fat intake of less than 30% of total kilojoules for adults and adolescents over 14 years, 35-40% for 2-5 year olds, and 35% for children aged 5-14.
Unsaturated fats are healthier fats, and they come from plant sources. They are usually liquid at room temperature. Unsaturated fats include mono-unsaturated and polyunsaturated fats.
Both types of unsaturated fats have been shown to help lower blood cholesterol levels. This is especially true when unsaturated fats take the place of saturated fats in the diet.
- Good sources of mono-unsaturated fats are olives, olive oil, most nuts, nut oils, especially peanuts, avocado and canola
- Good sources of polyunsaturated fats are safflower, corn, and sunflower oils, soybeans, and many nuts and seeds, such as grape seed and sesame seeds and their oils.
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 and it must be acquired from foods. Some studies suggest that omega-3 may help lower the risk for heart disease and heart attacks.
The Heart Foundation recommends up to 8-10% of total daily kilojoules from polyunsaturated fats and up to 14% from mono-unsaturated fats.
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. Saturated fat (including trans fats) in the diet should be limited to no more than 8% of total kilojoules.
Eating a lot of saturated fat may raise "bad" cholesterol levels in the blood. This "bad" cholesterol is low-density lipoprotein (LDL) cholesterol. LDL is what causes plaque to build up in the arteries to cause arteriosclerosis. Having high cholesterol levels is a major risk for heart disease. The DELTA study, sponsored by the National Heart, Lung and Blood Institute in the US, found that eating less saturated fat reduces both total and LDL cholesterol.
Two other types of fat are hydrogenated and trans fats.
Recent studies suggest both these types of fats may raise blood cholesterol levels.
- Hydrogenated fats are unsaturated fats that are processed to make them more solid. An example of a hydrogenated food is margarine.
- Trans fats are formed during the process of hydrogenation. They are also found naturally in butter, milk, lamb and beef.
Fats are shown at the very top of the Australian Guide To Healthy Eating. This means that these foods should be used sparingly for a healthy diet. But following a diet that is extremely low in fat can cause vitamin and mineral deficiency. It is important to include some fat in the daily diet.
Reading food labels is a good way to help lower the amount of fat in the diet. All food labels are required to list the total fat in grams. A food with 3% or less of fat is considered a "low-fat" food. Be careful of fat-free foods. Just because a food is fat-free does not mean it is kilojoule-free!
Tips for lowering fat intake include:
Learning about fat takes the guesswork out of following a healthy, low-fat diet.
- buying lean cuts of meat
- trimming off visible fat before cooking meat
- adding fish to the diet
- eating a meatless meal at least once a week
- choosing low-fat or skim dairy products
- baking, steaming, roasting, boiling, or grilling foods instead of frying them in fat
- when you do use oil, use an oil spray to saute` rather than frying
- use a non-stick pan with just a dash of healthy oil to get the best flavour without excess fat
Author: Kimberly Tessmer, RD, LD
Reviewer: eknowhow Medical Review Panel
Editor: Dr John Hearne
Last Updated: 22/11/2004
Potential conflict of interest information for reviewers available on request