11/10/2012
What is fat?
Fat is an oily, greasy material found in animals (including humans) and plants. Much as we might prefer to have less of it, fat is a fact of all life. Almost nothing lives without it.
There are different types of fat including saturated, monounsaturated, polyunsaturated, and trans. Foods almost always contain more than one of these fats, but some foods have more “bad” fat than others. If you really want to be fat-savvy, you need to know what’s what.
Saturated fat is “bad” fat. Too much of it increases your cholesterol levels, raises the risk of blood clots, atherosclerosis (artery blockage), and coronary heart disease. Saturated fats are found mainly in animal products such as full cream milk, cheese, butter, cream, fatty meats and sausages, and also in processed foods. Coconut, palm and other tropical oils are the only plant foods that contain significant amounts of saturated fat. Saturated fats are usually solid or waxy at room temperature.
Trans fat is “the other bad fat”. This fat also raises blood cholesterol levels and increases the risk of heart disease. It is made by adding hydrogen to vegetable fats – a process called hydrogenation. Trans fats are found mostly in baked goods and fried foods, and in shortenings and margarines that are “hydrogenated” or “partially hydrogenated.”
Polyunsaturated fats are “good” fats and come in two forms: omega-6 and omega-3. Omega-6 polyunsaturated fats tend to lower blood-cholesterol. Rich sources include safflower, sunflower, and corn oils. Omega-3 polyunsaturated fats can also lower blood-cholesterol when used in place of saturated fats. Omega-3 fats have many other health benefits, such as lowering blood-triglycerides and blood-pressure levels as well as reducing the risk of heart disease. They may also protect against some cancers. Sources of omega-3 fats include canola, flaxseed, walnut, and soybean oils, and oily fishes like mackerel, herring, tuna, and salmon. (Note: Sources of omega-6 – safflower, sunflower, and corn oils – are overabundant in the typical diet. Aim for a 1:1 ratio of omega-6 to omega-3 fats in your diet).
Monounsaturated fats are also “good” fats as they tend to lower "bad" LDL-cholesterol and maintain the protective "good" HDL-cholesterol in the bloodstream - but only if they replace saturated fats in the diet. Foods rich in monounsaturated fat include olive and canola oils, peanuts, and avocados.
Cholesterol is not a fat per se; it is more like a cousin of fat. Both fats and cholesterol belong to the lipid family. Cholesterol fulfils many important functions in the body. For example, it is used in the making of hormones, vitamin D, and bile acids which help in the digestion of fat, as well as in the maintaining of cell walls. The problem is that your liver already makes around 1000mg of cholesterol per day, which is almost as much, if not all, of the cholesterol your body needs to maintain these vital functions. So, when you consume too much dietary cholesterol as well (mainly from foods high in saturated fat), your body cannot get rid of the excess. The fats build up in various cells and tissues of the body, leading to heart complications and other health problems. Cholesterol is found in high-fat dairy products, egg yolks, high-fat meat, and poultry skins.
