Fats: the good, the bad & the ugly

Fats: the good, the bad & the ugly

by Hayley Blieden

The good fat versus bad fat debate has been going on for decades. Health professionals will argue one point of view until they are blue in the face, highlighting credible references and scientific evidence. Moments later, a different health professional will argue the opposite opinion with arguments equally as impressive and as reliable as the first. The constant conflicting advice makes it really difficult to determine the good from the bad and the ugly.

As a dietitian, I am going to try to explain this debate as simply as possible. But to be honest with you, as the research evolves, I too am finding myself questioning my beliefs and understanding.

Let me start by explaining the basic history of the low fat debate. In the 1960’s there was a dramatic spike in heart disease in the US. This resulted in the beginning of the end; the low fat, high carbohydrate diet. I say the beginning of the end, as this was also the introduction to “fat free” and “low fat” foods, which encouraged consumers to devour excessive amounts of processed, high sugar foods. In an effort to avoid natural fat, we started eating processed carbohydrate.

This approach clearly didn’t work. As we continued to eat the low fat, high carbohydrate diet, our waist lines continued to expand, along with our mortality rates, due to diet-related disease. So this sent health professionals and researchers back to the drawing board. Which has led us to the revolutionary new way of eating, one which encompasses carbohydrate, protein and fat in nearly equal quantities. An eating plan, which if needed a name, may be described as good fat, good carbohydrate.

Now, this does not mean you should reach for a Mars bar. Different fats affect us differently, and too much of a good thing will have negative consequences.

Basically there are two types of fats: saturated fats and unsaturated fats. Within each of these groups there are several more types of fats.

Unsaturated fats
Let’s start with the goodies, the fats that you should consume every day - the unsaturated fats. Unsaturated fats include monounsaturated fatty acid and polyunsaturated fatty acids. When these fatty acids are eaten in moderation they can have significant health benefits including reduced cholesterol and reduced risk of cardiovascular disease.

Polyunsaturated fats are found mostly in vegetable oils. One polyunsaturated fatty acid that is very popular at the moment is Omega-3 fatty acids. These guys reduce the risk of heart disease by reducing inflammation, lowering LDL (bad) cholesterol and increasing HDL (good) cholesterol.

Examples: Sunflower oil, corn oil, grape seed oil, flaxseed oil, soy bean oil.

Usage: Polyunsaturated fats should be used fresh eg. salad dressings. When cooked, these oils denature and form the “bad fat” trans fats, when this occurs they also take on a rancid taste.

Monounsaturated fats are the other “good fat”. Like polyunsaturated fats, they are also liquid at room temperature, yet solidify if refrigerated. These fats are a good source of Vitamin E and are required for the absorption of fat-soluble vitamins including Vitamin A, E, D and K. Many monounsaturated fats are ideal for cooking, as they will only denature at extremely high temperatures.

Examples: Rice bran oil, olive oil, safflower oil, canola oil, peanut oil, avocado oil, almond oil

Usage: These fats can also be used raw in salad dressings but are appropriate for cooking. Experiment with different nut based oils as they have a very distinct flavour.

Saturated fats
Unsaturated fats are a great substitute for saturated fats and trans fats, which are generally considered the bad fats. Saturated fats are predominantly found in animal products including meat, poultry skin and high fat dairy products and plant-based oils including coconut oil and palm oil. While it is well established that animal-based saturated fats contribute to heart disease, the exact effects of vegetable based saturated fats (such as coconut oil) are still being disputed.

Transfats are naturally found in meat and dairy products, however it is the man-made fats which are most dangerous - liquid vegetable oils that have been synthetically hydrogenated to create a solid. These are found in many processed foods including margarine, shortening, fried and fatty fast foods as they give texture and also improve shelf life. These transfats increase the risk of coronary heart disease by raising levels of LDL (bad) cholestorel and reducing levels of HDL (good) cholesterol.

It is important to remember that all fats and oils should be consumed in moderation. Different oils should be used for different purposes due to their flavour, smoke point and fatty acid composition. When heated, the fatty acid composition may change, turning a “good” fat into a “bad” fat. When cooking, opt for an oil with a high smoke point that is predominantly mono-unsaturated fats. Be careful to avoid health claims that promise life-altering benefits as no one food product can have such an effect. While many fats and oils have a number of health benefits they are also energy dense and should be incorporated into a balanced, healthy diet.




I'm confused, does that mean we should not be eating Olive oil and Canola oil based Margaines?
12 Jun, 2012 12:22:27 PM
Hi Jo,

This is a great question and one which I think many people Australia wide are confused with. With margarines, there is concern with the hydrogenation process and the effect it has on the fatty acid composition. However, The National Heart Foundation have stated that  Australian margarines have the lowest levels of trans fats in the world and that this should not be an issue when choosing between butter and margarine.

13 Jun, 2012 09:58:58 AM
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