When it comes to fat, a lot of people want to keep their distance, because all they can think of is obesity, heart disease, high blood pressure, and other illnesses. In fact, fat is an essential nutrient and the major source of energy to meet our body’s need. So let’s look at fat in depth.
Fat plays many roles in our body. These include:
A fat molecule is composed of three fatty acid molecules bonded to a glycerol molecule. It can mainly be divided into two types of fats.
Unsaturated fat can be subdivided into monounsaturated and polyunsaturated fat. It is recommended to replace saturated fat in the diet with polyunsaturated fat, monounsaturated fat from plant sources, or carbohydrates from foods containing naturally occurring dietary fibre, such as whole grains, vegetables, fruits and pulses. Also, it is preferred to replace trans-fat in the diet with polyunsaturated fat or monounsaturated fat primarily from plant sources (1). Polyunsaturated fats contain linoleic acid and linolenic acid, which are essential fatty acids as they cannot be produced by our body, and thus can only obtained from food. They facilitate blood flow, maintain normal blood pressure, and strengthen the immune system. Moderate consumption of unsaturated fats can reduce the level of total cholesterol in the blood.
Unsaturated fat is liquid at room temperature. It is usually found in vegetable oil (such as olive oil, canola oil, peanut oil, corn oil), seeds (such as watermelon seeds, pine nuts), and nuts (such as walnuts, cashews).
Please note: When vegetable oils are subjected to hydrogenation process, they will convert to trans fat. Excessive consumption of trans fat will increase the level of “bad” cholesterol and reduce the level of “good” cholesterol in the blood. Therefore, it is recommended to limit intake of trans fat, including food items with trans fat-containing margarine and shortening, as well as fried food and bakery products (e.g. pastries and crackers) in which such fats are used as ingredients or in the cooking process.
Saturated fat increases clotting activity in the blood stream and thus increases the risks of stroke and heart diseases if overconsumed. Saturated fat also stimulates the production of cholesterol by the liver, therefore, excessive intake of saturated fat increases the level of “bad” cholesterol in blood, and its adverse health effects are greater than consumption of cholesterol.
Saturated fat is solid at room temperature. It is usually found in animal fat such as meat, butter, lard and cream. There are also some plant-based saturated fat, such as coconut oil and palm oil.
Both unsaturated and saturated fat contain the same amount of energy, so overconsumption will cause weight gain. Beware of the “hidden” fat in foods such as instant noodle, spare ribs, poultries with skin, full-fat dairy products, ice cream, chocolate, salad dressing. The recommended fat intake should make up no more than 30% of your daily energy intake. Saturated fat, in particular, should make up less than 10% of your daily energy intake.
It is important to maintain a balanced diet. Eat more vegetables with moderate amount of lean meat, and use low-fat cooking methods in order to reduce your dietary fat intake. Avoid deep-frying and adding oil when marinating the meat. Use steaming, braising, baking, boiling, and stir-frying with small amount of oil. The use of a microwave oven and non-stick frying pan also helps reduce the amount of oil used in cooking.
(1) Guidelines Review Committee. Saturated fatty acid and trans-fatty acid intake for adults and children: WHO guideline [Internet]. 2023. Available from: https://www.who.int/publications/i/item/9789240073630
(Revised in August 2024)