Based on their structures and chemical compositions, dietary fats can be classified into monounsaturated fats and polyunsaturated fats (both can improve blood cholesterol levels), saturated fats and trans fats (both can raise blood cholesterol levels).
Fats are a rich source of energy. Each gram (g) of fat provides about 9 kilocalories (kcal) of energy. Fats help the body to transport and absorb various fat-soluble vitamins (such as A, D, E and K). Besides, they provide essential fatty acids (such as linoleic acid and omega-3 fatty acid) that are essential for normal growth and metabolism.
Fats are present in most food in variable amounts. Unsaturated fats are mainly found in plants, such as vegetable oils, avocado, nuts and seeds. Omega-3 fatty acids, a type of polyunsaturated fats, are found in fish.
Most saturated fats are from animal products, such as meat, dairy products and eggs. However, a few plants are also high in saturated fats, including coconut oil and palm oil. Trans fats, which mainly come from man-made fats created during the process of hydrogenation of vegetable oils, are commonly found in fried and packaged foods, including margarine, cookies, cakes and potato chips.
The World Health Organization (WHO) and the Food and Agricultural Organization (FAO) of the United Nations suggest healthy individuals should limit daily fat intake between 15% to 30% of total daily energy, with saturated fat to less than 10% and trans fat to less than 1%. As one gram of fat provides 9 kilocalories of energy, an individual with a daily energy intake of 2 000 kilocalories, for example, should limit the intake of dietary fat to less than 65.0 grams, with saturated fat to less than 22.2 grams and trans fats to less than 2.2 grams per day.
While all types of fats can contribute to overweight and obesity when eaten in large amounts, saturated fats or trans fats can raise blood cholesterol levels and increase the risk of heart disease.
Practical Tips for Keeping Fat Intake in Check
Fats are placed at the "Eat the Least" level at the top of the Food Pyramid. They should be taken in small amounts, with unsaturated fats being the preferred choices of fats. Here are some suggestions for keeping your fat intake in check:
- choose lean meat and skinless poultry;
- trim all visible fat off meat during preparation and before eating;
- use low-fat cooking methods such as steaming, boiling, broiling, braising, grilling, baking or roasting instead of frying and deep-frying;
- skim the solid fats from the top of soups or stews before re-heating them;
- remove the fats and oil from the surface of soups or stews;
- opt for skimmed or low-fat milk, cheese, yoghurt or other dairy products;
- avoid using animal fats, such as lark and butter;
- refrain from foods that are usually high in trans fats, such as fried foods, cakes, pastries or biscuits;
- read the nutrition labels to check the amount of fats contained in pre-packaged foods and select food products with lower fat.
Food, Nutrition, Physical Activity, and the Prevention of Cancer: a Global Perspective. Washington DC: World Cancer Research Fund and American Institute for Cancer Research; 2007.Diet, Nutrition and the Prevention of Chronic Diseases: Report of a Joint WHO/FAO Expert Consultation. WHO Technical Report Series No. 916.Geneva: World Health Organization; 2003.