Prominence of Low Fat Diets
Too much fat in your diet, especially saturated fats, can raise your cholesterol, which increases the risk of heart disease.
Current UK government guidelines advise cutting down on all fats and replacing saturated fat with some unsaturated fat.
Why we need some fat
A small amount of fat is an essential part of a healthy, balanced diet. Fat is a source of essential fatty acids, which the body cannot make itself.
Fat helps the body absorb vitamin A, vitamin D and vitamin E. These vitamins are fat-soluble, which means they can only be absorbed with the help of fats.
Any fat that's not used by your body's cells or turned into energy is converted into body fat. Likewise, unused carbohydrates and proteins are also converted into body fat.
All types of fat are high in energy. A gram of fat, whether it's saturated or unsaturated, provides 9kcal (37kJ) of energy compared with 4kcal (17kJ) for carbohydrate and protein.
The main types of fat found in food are:
- saturated fats
- unsaturated fats
Most fats and oils contain both saturated and unsaturated fats in different proportions.
As part of a healthy diet, you should try to cut down on foods and drinks that are high in saturated fats and trans fats and replace some of them with unsaturated fats.
Saturated fats
Saturated fats are found in many foods, both sweet and savoury.
Most of them come from animal sources, including meat and dairy products, as well as some plant foods, such as palm oil and coconut oil.
Foods high in saturated fats
- fatty cuts of meat
- meat products, including sausages and pies
- butter, ghee, and lard
- cheese, especially hard cheese like cheddar
- cream, soured cream and ice cream
- some savoury snacks, like cheese crackers and some popcorns
- chocolate confectionery
- biscuits, cakes, and pastries
- palm oil
- coconut oil and coconut cream
Cholesterol and saturated fats
Cholesterol is a fatty substance that's mostly made by the body in the liver.
It's carried in the blood as:
- low-density lipoprotein (LDL)
- high-density lipoprotein (HDL)
Eating too much saturated fats in your diet can raise "bad" LDL cholesterol in your blood, which can increase the risk of heart disease and stroke.
"Good" HDL cholesterol has a positive effect by taking cholesterol from parts of the body where there's too much of it to the liver, where it's disposed of.
Saturated fat guidelines
Most people in the UK eat too much saturated fats.
The government recommends that:
- men should not eat more than 30g of saturated fat a day
- women should not eat more than 20g of saturated fat a day
- children should have less
Trans fats
Trans fats are found naturally at low levels in some foods, such as meat and dairy products.
They can also be found in partially hydrogenated vegetable oil. Hydrogenated vegetable oil must be declared on a food's ingredients list if it's been included.
Like saturated fats, trans fats can raise cholesterol levels in the blood.
The government recommends that:
- adults should not have more than about 5g of trans fats a day
But most people in the UK do not eat a lot of trans fats. On average, we eat about half the recommended maximum.
Most of the supermarkets in the UK have removed partially hydrogenated vegetable oil from all their own-brand products.
People in the UK tend to eat a lot more saturated fats than trans fats. This means that when you're looking at the amount of fat in your diet, it's more important to focus on reducing the amount of saturated fats.
Unsaturated fats
If you want to reduce your risk of heart disease, it's best to reduce your overall fat intake and swap saturated fats for unsaturated fats.
There's good evidence that replacing saturated fats with some unsaturated fats can help to lower your cholesterol level.
Mostly found in oils from plants and fish, unsaturated fats can be either monounsaturated or polyunsaturated.
Monounsaturated fats
Monounsaturated fats help protect your heart by maintaining levels of "good" HDL cholesterol while reducing levels of "bad" LDL cholesterol in your blood.
Monounsaturated fats are found in:
- olive oil, rapeseed oil and spreads made from these oils
- avocados
- some nuts, such as almonds, brazils, and peanuts
Polyunsaturated fats
Polyunsaturated fats can also help lower the level of "bad" LDL cholesterol in your blood.
There are 2 main types of polyunsaturated fats: omega-3 and omega-6.
Some types of omega-3 and omega-6 fats cannot be made by your body, which means it's essential to include small amounts of them in your diet.
Omega-6 fats are found in vegetable oils, such as:
- rapeseed
- corn
- sunflower
- some nuts
Omega-3 fats are found in oily fish, such as:
- kippers
- herring
- trout
- sardines
- salmon
- mackerel
Most people get enough omega-6 in their diet, but it's recommended to have more omega-3 by eating at least 2 portions of fish each week, with 1 portion being an oily fish.
Vegetable sources of omega-3 fats are not thought to have the same benefits on heart health as those found in fish. Find out more about healthy eating as a vegetarian.
Buying lower fat foods
The nutrition labels on food packaging can help you cut down on total fat and saturated fat (also listed as "saturates", or "sat fat").
Nutrition information can be presented in different ways on the front and back of packaging.
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
"Lower fat" labels
For a product to be labelled lower fat, reduced fat, lite or light, it must contain at least 30% less fat than a similar product.
But if the type of food in question is usually high in fat, the lower fat version may still be a high-fat food (17.5g or more of fat per 100g).
For example, a lower fat mayonnaise may contain 30% less fat than the standard version, but it's still high in fat.
Also, foods that are lower in fat are not necessarily lower in calories. Sometimes the fat is replaced with sugar and the food may end up having a similar energy content to the regular version.
To be sure of the fat and energy content, remember to check the nutrition label on the packet.
Cutting down on fat is only one aspect of achieving a healthy diet.
Find out more about what food labelling terms mean, and how to get a balanced nutritious diet using the Eatwell Guide.
Use the Change4Life Food Scanner app app to find healthier food choices when you're shopping.
Page last reviewed: 14 April 2020
Next review due: 14 April 2023
Source: https://www.nhs.uk/live-well/eat-well/different-fats-nutrition/