What are fats?

Reviewed by our clinical team

Fat is a macronutrient. Macronutrients are the nutrients we need in the biggest quantities, micronutrients are needed in smaller quantities. 

Fat helps your body absorb essential vitamins and minerals, it's a source of fatty acids (which your body can't make itself) and they're also a source of energy. But too much fat in your diet (particularly certain types) can raise your cholesterol and risk of heart disease. 

In this guide we'll look at why we need some fats, what the best sources of fat are and the quantity you need of each kind of fat. 

Do I need some fat in my diet?

Yes, you do need some fat in your diet because it:

• Is an essential source of fatty acids
• Helps your body absorb fat-soluble vitamins like vitamin A, vitamin D and vitamin E.

All fats are high energy too, with each gram of fat giving you around nine kilocalories (kcals) of energy. But it's important to remember that any fat not used by your body is turned to body fat. The same happens with carbohydrates and protein. 

Types of fat

There are three main types of fat:

• Saturated fats
• Trans fats
• Unsaturated fats

Lots of fats will have both saturated and unsaturated fats in them. But it's saturated fats which are most associated with high cholesterol. So swapping out some saturated fats, and cutting down on fats in general can help your body stay healthy. 

We'll now go into the types of fats in more detail and look at the key sources of these fats in the UK. 

Saturated fats

What are saturated fats?

Saturated fats are a type of fat that tend to come from animal produce, but occasionally they come from plant-based products too. 

Most of us in the UK are eating too many saturated fats. Eating too many saturated fats can impact the amount of cholesterol in your body. Cholesterol is a fatty substance produced by the liver which is carried in the blood as low-density lipoprotein (LDL) and high-density lipoprotein (HDL). 

Lots of saturated fat in your diet can increase the levels of LDL (so-called 'bad' cholesterol) in your body which increases your risk of stroke and heart disease. 

HDL is considered 'good' cholesterol, it helps the body remove any excess cholesterol in the body, taking it to the liver where the liver gets rid of it. 

Sources of saturated fats

Saturated come from things like meat, dairy, palm oil and coconut oil. 

Some common examples of sources of saturated fats include:

• Meat - fatty cuts, processed meats like sausages and bacon, cured meats like chorizo and parma ham
• Cooking oils - ghee, lard, palm oil, coconut oil
• Some dairy products - butter, cheese (particularly hard cheeses), cream, ice cream, chocolate
• Some snacks - biscuits, cakes, pastries, cheese crackers and some popcorns
• Coconut cream

How much saturated fat should I eat?

How much saturated fat you should have in your diet depends on your sex and age. 

• Men shouldn't have more than 30g a day
• Women shouldn't have more than 20g a day
• Children should have less than adults

Trans fats

What are trans fats?

Trans fats, like saturated fats, are found in low levels in some animal produce. But they're also found in hydrogenated vegetable oil, a type of cooking oil that can be added to food to prolong its shelf live. 

Like with saturated fats, too many trans fats can cause high cholesterol. 

Sources of trans fats

Because trans fats are most common found in hydrogenated vegetable oils, they're often found in foods like:

• Margarine
• Doughnuts, cakes and pastries
• Bread
• Ice cream
• Some fast food

How much trans fat should I be eating?

We don't tend to eat that many trans fats in the UK, with most of us eating more saturated fats than trans fats. 

The recommended allowance for trans fats is 5g a day, but in the UK, on average, we only eat around half that amount. That's because lots of supermarkets and other food chains have reduced, or completely cut out, the use of hydrogenated vegetable oils in their products.

Unsaturated fats

What are unsaturated fats?

Unsaturated fats tend to be considered the healthier option when talking about fats. Swapping saturated and trans fats for unsaturated fats can help reduce your risk of heart disease and lower cholesterol. 

You can find them in a variety of plant and fish produce. There are two types of unsaturated fats - monounsaturated fats and polyunsaturated fats. 

Monounsaturated fats

These fats are used by your body to keep you heart healthy. That's because they help your body increase the levels of HDL cholesterol and decrease levels of LDL cholesterol. 

Sources of monounsaturated fats

You can get monounsaturated fats from a variety of different foods, including:

• Olive oil
• Rapeseed oil
• Avocados
• Almonds
• Brazil nuts
• Peanuts
• Cashews
• Hazelnuts
• Pistachios

Polyunsaturated fats

Like monounsaturated fats, polyunsaturated fats can also reduce the amount of LDL cholesterol in your body. 

You usually get polyunsaturated fats from omega-3 and omega-6, but your body can't make all the types of these fats itself, so you need to get them from food in your diet. 

Sources of omega-3

Omega-3 fats are typically found in oil fish like kippers, mackerel, sardines, salmon and trout. 

You can get plant-based sources of omega-3, for example, chia seeds, linseed and shelled hemp seeds. However it's thought that these plant-based sources of omega-3 don't give have the same positive impacts on heart health as those found in fish. 

Sources of omega-6

You can get omega-6 from vegetable oils like rapeseed, corn, sunflower and some nut oils. 

How many polyunsaturated fats do I need?

Most people tend to get enough omega-6 in their diet, but not enough omega-3. The NHS recommends eating at least two portions of fish a week, with one of these being oily fish to help you get the omega-3 you need. 

Food labels and buying lower fat foods

In the UK the labels on food are there to help guide you on the ingredients in the food or drinks you're eating. They'll detail nutritional values, and can hep you be sure of the fat and energy content. 

For something to be labelled as low fat, reduced fat or lite/light, it has to have 30% less fat than a similar product. But don't forget, if something is already high in fat, the lower fat version might still be a high-fat food. Low fat foods aren't necessarily low calories either. So it's important to always check those labels closely. 

You might have fat presented in different ways on nutritional labels - they might look at total fat or saturated fat. 

Here's some guidance from the NHS on labelling:

Total fat

• High fat: more than 17.5g of fat per 100g
• Low fat: 3g of fat or less per 100g, or 1.5g of fat per 100ml for liquids (1.8g of fat per 100ml for semi-skimmed milk)
• Fat-free: 0.5g of fat or less per 100g or 100ml

Saturated fat

• High in sat fat: more than 5g of saturates per 100g
• Low in sat fat: 1.5g of saturates or less per 100g or 0.75g per 100ml for liquids
• Sat fat-free: 0.1g of saturates per 100g or 100ml

You can find out more about eating a healthy diet with this guide, or visiting our lifestyle advice hub. 

References

https://www.nhs.uk/live-well/eat-well/food-types/different-fats-nutrition/
https://www.nhs.uk/conditions/high-cholesterol/cholesterol-levels/
https://www.nhs.uk/live-well/eat-well/how-to-eat-a-balanced-diet/eat-less-saturated-fat/
https://www.nhs.uk/live-well/eat-well/how-to-eat-a-balanced-diet/the-vegan-diet/
https://www.diabetes.co.uk/food/trans-fats.html
https://www.bhf.org.uk/informationsupport/support/healthy-living/healthy-eating/fats-explained