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Good fats and bad fats explained

What is fat?

Fat is a rich source of energy; 1 gram provides 37 kJ (9 kcal). Fat is made up of building blocks called fatty acids and these are classified as saturated, monounsaturated or polyunsaturated depending on their chemical structure. Some of these are essential components of the diet but others can be detrimental to our health if too much is consumed.

All types of fat provide the same number of calories (9kcal/g) regardless of where they come from. This means that too much of any type of fat can encourage weight gain. Foods that contain a lot of fat provide a lot of energy and are called energy-dense foods. Consuming too many energy-dense foods can lead to excess energy intake. This energy will be stored as body fat and, over time, promote the development of obesity, which increases the risk of developing conditions such as heart disease, type 2 diabetes and cancer.

How much fat do we need each day?

The recommendations for maximum daily fat intake for adults in the UK (called Reference Intakes; formerly known as Guideline Daily Amounts) are shown below.

 

Reference Intake

Males

Females

Total fat

95g

70g

Saturates

30g

20g

Are we eating too much fat?

The Department of Health recommends that fat intake should not exceed 35% of our total daily energy intake from food and saturated fat should not exceed 11% of total energy intake from food. As a population, our total fat intake is close to these recommendations, but the amount of saturated fat we consume is too high. Foods high in saturated fat, such as butter, fried foods, and some cakes, biscuits and pastries, should only be eaten in small amounts, as this type of fat can increase blood cholesterol levels.

As a guideline, men should consume no more than 30g of saturated fat a day and women no more than 20g.

People who are overweight or obese may also need to think about reducing their total fat,  as well as saturated fat, intake to help them lose weight and avoid further weight gain.

We are not always aware of the amount of saturated fat that we are eating or how much particular foods contribute towards our daily intake. The saturated fat content of a number of popular foods and meals is listed below:

Food item

Average serving size

Saturated fat per serving

% of Reference Intake for women

Chunk of cheddar cheese

40g

8.7g

43.5%

Dry roasted unsalted nuts

40g

3.4g

17%

Bolognese sauce with meat

240g

10.0g

50%

Grilled beefburger

100g

10.9g

55%

Croissant with butter

70g

11.1g

56%

Slice of sponge cake with buttercream

60g

5.6g

28%

1 chocolate digestive

18g

2.2g

11%

Front-of-pack labelling now makes it quick and easy to check foods before you buy them and select healthier options:

  • Products with between 3 and 17.5g of fat per 100g are colour coded amber on the label
  • Products with less than 3g of fat per 100g are colour coded green on the label
  • Products with more than 17.5g of fat per 100g are colour coded red on the label

What types of fat should we be cutting back on?

Saturated fats

Too much saturated fat can increase the amount of cholesterol in our blood, which increases the risk of heart disease and stroke.  There are two types of cholesterol in the body: HDL (good) cholesterol and LDL (bad) cholesterol. ‘Bad’ cholesterol can build up in our blood vessels and cause them to narrow. This increases the risk of blood clots which can lead to heart attacks or strokes. ‘Good’ cholesterol retrieves the ‘bad’ cholesterol from the body and carries it to the liver so that too much doesn't build up in the bloodstream. High intakes of saturated fat increase the level of ‘bad’ cholesterol in our blood.  Recent stories in the media have argued that saturated fat may not be strongly associated with blood cholesterol and heart disease, but these reports are misleading. Several studies have shown a high saturated fat intake to be linked with high cholesterol and coronary heart disease. Studies have shown that replacing saturated fat with unsaturated fat in the diet reduces blood cholesterol and lowers the risk of heart disease and stroke.

What foods contain saturated fat?

 

All foods contain a mix of fats. But foods with a higher proportion of saturated fats include fatty meats, full-fat dairy products and some processed foods. Fats with a greater proportion of saturated fatty acids tend to be solid at room temperature (e.g. butter and lard) but some oils (e.g. palm and coconut oil) are also high in saturates.

Trans fats

Trans fats are found naturally in small amounts in meat and dairy products, but much larger amounts are produced in the production of partially hydrogenated vegetable oils. Trans fats produced in this way have been shown to have a more adverse effect on blood cholesterol levels than saturates.  But concern about the health implications of consuming high intakes of trans fats has led to changes in manufacturing practices in recent years and good progress has been made to remove these fatty acids from our food chain. For example, margarines and spreads sold in the UK do not now contain partially hydrogenated vegetable oil. This has meant that average trans fatty acid intake in the UK diet is now well below the recommended limit and many foods are now free of trans fats.

What types of fat are healthier choices?

Unsaturated fats

All fats contain a mixture of saturated and unsaturated fatty acids but choosing foods which contain higher amounts of unsaturated fat, and less saturated fat, is preferable.

Unsaturated fats contain a higher proportion of unsaturated fatty acids and are usually liquid at room temperature. Monounsaturated and polyunsaturated fats help to maintain healthy cholesterol levels and are found in vegetable oils such as olive, rapeseed and sunflower oils, avocados, nuts and seeds. Polyunsaturated fats provide us with essential fatty acids like omega-3 which are important for health.

Omega 3 fatty acids

These are a group of polyunsaturated fatty acids. These are found in oily fish (e.g. mackerel, salmon and sardines) and in smaller amounts in sunflower oil, flax, linseed oil and walnuts. Omega 3 fatty acids are associated with good heart health as they can help to prevent blood clotting and regulate heart rhythm. They are also important during pregnancy and breastfeeding to support child development.  In order to get the benefits from these fatty acids we should all aim to eat at least one portion of oily fish per week.

  • Good sources include mackerel, salmon, pilchards, sardines, kippers, herring, trout, fresh crab, whitebait and swordfish

How can we increase our intake of healthier fats?

We should all try to cut down on the amount of saturated fat that we consume and choose healthier foods containing unsaturated fatty acids instead, from foods like avocados, nuts and fish. These foods are typical of the Mediterranean diet, which is associated with good heart health and a lower risk of heart disease.

Vegetable oils such as rapeseed, olive, sunflower, soya, sesame oils, and margarines or spreads made from these oils are healthier alternatives to oils or fats rich in saturated fats (e.g. lard, butter, palm and coconut oil) as they contain a higher proportion of unsaturated fatty acids.

It’s easy to make small changes to cut back on saturated fat. Here are some examples of simple swaps you can make to reduce the amount of saturated fat you consume:

Swap

For

Whole milk, cream and full fat cheese

Lower fat dairy products like skimmed, semi-skimmed or 1% fat milk and reduced fat cheese

Fatty cuts of meat

 

Lean cuts with no visible fat

Roasted and fried foods

 

Grilled, steamed or baked foods

Butter, lard, ghee, coconut and palm oils

 

Oils rich in unsaturated fatty acids such as olive, rapeseed or sunflower oils and spreads made with these

Cakes, biscuits and pastries

 

A handful of unsalted nuts

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