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Good fats and bad fats

by cheree Published on 22 January 2008

Fat is full of calories (1g = 9 kcal) and is to blame for weight gain and heart problems, but our body needs fat to function. You have to eat a certain amount of the right fat. Here's the lowdown on what's good and bad.

Fat is full of calories (1g = 9 kcal) and is to blame for weight gain and heart problems, but our body needs fat to function. You have to eat a certain amount of the right fat. Here's the lowdown on what's good and bad.

Their role
Consuming lipids (the scientific name for fat) in any form, is essential for the body for a number of reasons:
-they create cellular membranes.
-they're used in tissue composition, especially in the brain.
-they help produce hormones and other chemicals.
-they regulate bile salt synthesis, which is important in the digestive process.
-they transport Vitamins A, D, E and K in the body.

Fatty acids and health

Lipids are made up of tiny elements called fatty acids. Depending on their chemical formula, there are several families, each of which has different qualities:
-saturated fatty acids are characterised by their resistance to deterioration which affects fats exposed to air and light, and are generally solid at room temperature. Known as 'bad fats', they increase cholesterol production and encourage heart problems, particularly in people who are already at risk because of family history, diabetes, smoking and stress.
-unsaturated fatty acids, known as ‘good fats', are divided into two categories. Monounsaturates protect the arteries by lowering levels of bad cholesterol. Polyunsaturates also help protect the heart. Essential fatty acids are polyunsaturates. Our body is unable to produce these, but it needs them to function properly. They are Omega 3s, which improve blood flow, mood and skin repair and Omega 6s which reduce bad cholesterol and aid cell structure.
Certain polyunsaturated fatty acids are unfortunately sometimes refined by the food industry into trans fat, which is said to increase levels of bad cholesterol and encourage the development of certain types of cancer.

Your main sources of fat
No food contains just one type of fatty acid: you always get a mixture, in varying proportions. However, certain fatty acids are found in higher concentrations in certain foods:

Type of fatty acidSources

Saturated fatty acids

milk (especially whole milk), cheese, cream, butter, meat, coconut oil and palm oil

Monounsaturates

olive oil, rapeseed oil, peanut oil, oil-producing fruits (almonds, pistachios, hazelnuts, walnuts)

Polyunsaturates - Omega 3 series

oily fish (tuna, mackerel, sardines, herring), rapeseed oil, soya oil, linseed oil (flax seed oil), walnut oil

Polyunsaturates - Omega 6 series

eggs, butter, dairy products, oil-producing fruits, rapeseed oil, sunflower oil, walnut oil, corn oil, grapeseed oil, borage oil, evening primrose oil

Trans fats

biscuits, cakes, industrially produced bread containing fat, some margarines, spreads and pastes, cream-based desserts, industrially produced ice-cream, crisps

Recommendations
Fat is essential and should never be cut out of your diet, even if you want to lose weight. According to official figures, fat should make up 30-35% of your daily energy intake (with 10-15% from protein and 50-55% from carbohydrates). However, to stay healthy and particularly to keep your heart healthy, it’s important you vary the fatty acids you consume: 25% saturated fatty acids, 50% monounsaturated fatty acids, 25% polyunsaturated fatty acids.
Which in practice means:
- You should limit your consumption of fatty dairy products, eggs and meat, and avoid refined products such as crisps, biscuits, cakes and ready meals at all costs.
- Eat oily fish (at least once a week) and rapeseed or walnut oil (2 tablespoons per day in cooking or seasoning).
- 10g butter a day is enough on your bread or melted over your vegetables. Watch out for refined products, though.

by cheree