Fats - the good, the bad, and the ugly

Discover which fats to embrace and which ones to avoid altogether.

Fats are an essential part of our diet. Despite this, fats are the most villainised nutrient. We don't usually speak about fats in a positive light, and we are constantly pushed towards low-fat and fat-free food choices.

The truth is that not all fats are created equal. There are many different types, and in moderation, some fats may be good for your health.

But it can be hard to know which fats to embrace and which ones to avoid altogether…

In this week's blog, we shed some light on the topic.

Why do we need fat in our diet?

Fats support us in absorbing and transporting 'fat-soluble vitamins' around our bodies. These include Vitamin A, Vitamin D, Vitamin and Vitamin K.

Fats are also an essential part of our body cells, and fat helps us to form healthy brain and nerve cells. When the number of calories we eat is low, our bodies can use fat to supply energy. Fat also provides a physical cushion to our major organs such as the heart and kidneys for protection.

So, there we have it, fat can be helpful. But how can we separate the bad stuff from the good stuff?

The good fats

Good fats are known as unsaturated fats. Firstly, this means these fats are usually liquid at room temperature (they are oils).

Secondly, these are not associated with raised blood cholesterol and therefore do not contribute to cardiovascular diseases, such as heart disease and stroke. In moderation, some may even be beneficial.

The two main types of unsaturated fats are:

  1. monounsaturated fat
  2. polyunsaturated fat

We find monounsaturated fats in olive oil, avocados, and some nuts and seeds such as Brazil nuts. Eating monounsaturated fats reduces ‘bad’ LDL cholesterol in our blood while maintaining 'good' HDL cholesterol [1].

Polyunsaturated fats are even less saturated than monounsaturated fats. There are two main types of polyunsaturated fat: omega-3 fat and omega-6 fat.

We find omega-6 fats in seeds, nuts and oils such as sunflower oil. One omega-6 fat called linoleic acid (LA) is essential in our diet. It is called an essential fatty acid - this means our body cannot make it, so to stay healthy, we must obtain some from food sources such as sunflower oil and corn oil.

There is also an essential omega-3 fat called a-linolenic acid (ALA). We find this fat in plant foods such as flax/linseed and walnuts. We can find other omega-3 fatty acids such as docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) in oily fish, such as salmon and mackerel.

EPA and DHA are not essential fatty acids because our bodies can use ALA to make them. But this conversion occurs slowly and varies from person to person. The current advice is to have one portion of oily fish a week to get our recommended amount of EPA and DHA.

Most people get more than enough omega-6 fats in their diet, but many do not eat enough omega-3 fats. You can test your blood levels of ‘good fats’ with a simple Omega 3 and 6 Blood Test from Medichecks.

The bad fats

Saturated fats are found naturally in animal products (meat and dairy products such as butter). Still, there are plant sources too, namely coconut oil and palm oil. Manufacturers can often add saturated fats to processed foods such as pastries, savoury snacks, chocolate and pies (sorry!).

How are these fats different? Well, the giveaway here is that these fats are often solid at room temperature (think about a block of butter or the fat on your bacon).

Overconsumption of these fats can lead to ‘fatty deposits’ in our arteries and increase our risk of cardiovascular diseases such as heart attack and stroke.

Many experts believe this happens because saturated fats can raise 'bad' LDL cholesterol in our blood. You can read all about cholesterol here.

Unlike the essential fatty acids discussed above, saturated fats are not essential for our health. In other words, if we didn’t have any in our diet, we'd probably do just fine (or for most of us, our health would probably do a little better).

You can measure your diet's impact on your blood cholesterol and, therefore, your risk of cardiovascular disease with an at-home Cholesterol Blood Test. You can take the test in the comfort of your own home and receive your confidential results on your personalised Medichecks dashboard. You can even check your risk of developing heart disease with a Heart Disease Risk Blood Test, which also tests the level of inflammation in your blood.

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The dangerous fats

Trans fats are made from a type of oil called partially hydrogenated vegetable oil. Manufacturers can add this oil to cakes, biscuits, pies, and fried foods [3]. Some trans fat also exists naturally in foods such as meat and dairy foods.

Trans fats are dangerous for our health because they can lead to:

  • Heart disease Stroke Liver dysfunction Type 2 diabetes Alzheimer’s disease [2]
  • Trans fat not only raises bad LDL cholesterol, it also reduces levels of healthy HDL cholesterol [2].

Trans fat used to be a bigger problem than they are today. Nowadays, manufacturers rarely add trans fats to foods, and they must declare them on a food's ingredients list. So, to be sure you are avoiding them, check the ingredients list. However, many takeaway foods contain trans fats, which do not have food labels.

How much fat do we need in our diet?

The main problem with all types of fat is that fat is very calorie-dense. Compared to carbohydrates, which provide four calories per gram, all fat types (whether good, bad or ugly) provide over twice as many calories, with nine calories per gram.

All this means is that fat is very easy to consume too much. And because our brains are hard-wired to enjoy calorific foods, it is sometimes difficult to stop (and put the biscuits down) when we need to.

If we want our diet to remain healthy, we simply need to stay mindful of the amounts of fat we include in our diet.

Experts recommend having no more than 70g of fat in our diet daily. If you’re a woman, only 20g of this should be saturated, and if you're a man, no more than 30g should be saturated. Most people in the UK consume too much-saturated fat [2]. Experts also recommend that we only have 5g of trans fat in our diet per day.

But if you’re managing your body weight, don't be misled into thinking that low-fat or fat-free products are lower in calories. The fat can often be replaced with other calorific nutrients such as sugar to keep them tasty.

You can find out how much fat is in your food by reading the food label and keeping your eye on the amount of fat you add to foods through spreads and oils.

In summary, it’s true what they say – it is all good in moderation.

If you are interested in seeing the impact your dietary choices are having on your body, you can assess your blood cholesterol levels with an at-home Cholesterol Blood Test. You can take the test in the comfort of your own home and receive your confidential results on your personalised Medichecks dashboard. You can check your overall risk of developing heart disease with a Heart Disease Risk Blood Test. If your results are out of the healthy range, our expert doctors can recommend healthier lifestyle changes to bring your results back into a healthy range.


[1] https://www.nhs.uk/live-well/eat-well/different-fats-nutrition/ [2] https://www.diabetes.co.uk/food/trans-fats.html [3] https://www.sentinelhealthcare.co.uk/wp-content/uploads/2017/08/diabetes-2-leaflet-trans-fats.pdf

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