Healthy vs. Bad Fats During the Ketogenic Diet

Fats. They are the big star in the ketogenic diet.

For years they have been very unpopular among those who want to eat healthy foods. The assumption that eating fat directly leads to an increase in body fat has long since become obsolete.

But what about cholesterol, many people will say.

If you eat a lot of saturated fats and you get more cholesterol, does this have no consequences for your cholesterol levels and possibly also for your risk of cardiovascular disease?

The effect of cholesterol on health is much more nuanced than has been assumed over the years. Improved and advanced research methods have provided new insights into the effect of fat consumption on cholesterol levels in the body and also about the role that cholesterol plays in the human body.

For example, it appears that cholesterol itself is not a culprit in the body, but that the transport molecules that have to transport cholesterol through the body – so-called lipoproteins – can be a risk factor. These lipoproteins consist of proteins and fat.

The health of your cardiovascular system is determined by the presence of certain types of transport molecules in the blood. Low-density lipoproteins (they form the bad LDL cholesterol ) and greasy structure cause blockages and can attach to the walls of the blood vessels and cause further damage here.

The ketogenic diet can help to lower LDL cholesterol and increase the presence of healthy cholesterol that is transported by high-density transport molecules ( HDL cholesterol ).

You can read more about this principle of cholesterol and fats in our article Keto & Cholesterol: The 2 Biggest Misconceptions About Fat That You Should Forget.

However, it is crucial for a healthy ketogenic diet that you use the right fats to compile your diet. Because there is quite a distinction between the different types of fats that are available as food.

Of course, it does matter what type of fat you eat! There are simply healthy fats and unhealthy fats.

Good fats during the Ketogenic diet

Three types of fats are permitted within the ketogenic diet: saturated fats, monounsaturated fats, polyunsaturated fats. Let’s see which foods are included.

Healthy Saturated Fats

For years, saturated fats have been in a bad light because they were thought to be bad for the cardiovascular system.

However, recent scientific studies have shown that there is  NO connection between the consumption of saturated fats and cardiovascular diseases  (1). In fact, there are even proven health benefits related to healthy saturated fats.

These are some health benefits of saturated fats in a keto diet:

  • improved HDL and LDL cholesterol levels
  • maintenance of bone density
  • stimulus for the health of your immune system
  • support for the formation of important hormones such as cortisol and testosterone
  • increase of HDL cholesterol in the blood, which prevents the accumulation of LDL in the veins
  • improved ratio of HDL to LDL (better known as the cholesterol ratio.

Recommended sources of saturated fats within the ketogenic diet:

  • Coconut oil
  • Butter
  • Ghee
  • Cream
  • Eggs
  • Cocoa butter
  • Lard

In addition, one of the saturated fats contains the so-called medium-chain fatty acids(MCTs), which mainly occur in coconut oil (and in small quantities in butter and palm oil) and which can be absorbed very easily by the body.

If you eat these fatty acids, they are immediately transported to the liver for immediate use as energy.

MCTs are great if you want to lose fat and put down sporting performance.

In addition, MCTs also have many other health benefits that we discuss in more detail in Article 7 Scientifically Proven Health Benefits of MCT Oil.

Healthy Simple Unsaturated Fats

Unlike saturated fats, monounsaturated fatty acids have had a good reputation for years. Scientific research has shown that they are good for your HDL cholesterol and better insulin sensitivity  (2)

The health benefits of monounsaturated fatty acids during a ketogenic diet are:

  • increase in HDL cholesterol
  • lowered blood pressure
  • reduced risk of heart disease
  • less belly fat
  • reduced insulin resistance

Recommended sources of monounsaturated fats within the ketogenic diet:

  • Extra virgin olive oil
  • Avocados and avocado oil
  • Macadamia nuts and macadamia oil
  • Goose fat
  • Lard

Healthy Polyunsaturated Fats

When it comes to eating polyunsaturated fatty acids during a ketogenic diet, it is important to remember that the species really matters here.

When heated, polyunsaturated fats can form free radicals, which are harmful components that promote inflammation and also increase the risk of cancer and heart disease. Many of these fats are therefore the best cold foods and cannot be used for cooking.

Polyunsaturated fats carry proven health benefits that are attributed to the presence of omega-3 and omega-6 fatty acids. These are essential nutrients, which means that your body can only get them through food.

However, it is very important to monitor the correct ratio between omega-3 and omega-6 fatty acids in your diet. The ideal ratio is 1: 1.

In the standard Western diet, however, this ratio is 1:17, an overdose of omega-6! This has an anti-inflammatory effect and is therefore not desirable.

It is therefore extremely important to distinguish between healthy polyunsaturated fats and the unhealthy variants.

Good sources of polyunsaturated fats are:

  • Flaxseed and linseed oil
  • Walnuts
  • Fatty fish (sardines, salmon, mackerel)
  • Chia seed
  • Nut oil
  • Avocado oil
  • Hemp seed (oil)

We have already discussed the unhealthy sources of polyunsaturated fatty acids in Chapter 6, but it can do no harm to point out these culprits once again: sunflower, soy, corn and peanut oil are rich in inflammatory omega-6 fatty acids. So avoid!

Try to obtain your multi-saturated fats from the above products, so that you get the anti-inflammatory omega-3 fatty acids.

Consuming omega-3 fatty acids has the following, hold on, 17 (!!!) proven health benefits :

  • Helps against depression and anxiety
  • Improves eye health
  • Brain development in newborns and unborn babies during pregnancy
  • Can prevent ADHD symptoms in children
  • Preventing risk factors for cardiovascular disease
  • Can help combat the symptoms of metabolic syndrome
  • Anti-inflammatory properties
  • Can help against autoimmune diseases
  • Can help against psychiatric disorders
  • Helps to inhibit neurodegenerative diseases such as Alzheimer’s
  • Possible protective function against certain types of cancer
  • Can help against asthma in children
  • Can help to combat osteoporosis and arthritis
  • Possible analgesic effect with menstrual pain
  • Can help improve sleep quality
  • Good for the skin
  • Can prevent fatty liver

Try therefore to focus on the consumption of healthy omega-3 fatty acids from fatty fish and you can supplement this with a fish oil supplement or, even better, with krill oil.

Natural Trans Fats

You may be surprised that I place the trans fats in the list of ‘good’ fats.

Although most trans fats are very unhealthy and harmful, there is a type of trans fat, the so-called vaccenic acid , that occurs naturally in some foods, including meat and dairy from grass-fed ruminants.

Vaccenic acid can have the following health benefits:

  • reduced risk of heart disease
  • lower risk of diabetes and obesity
  • possible protection against the risk of cancer

Recommended types of natural trans fats:

  • products from grass-fed ruminants
  • dairy fats such as butter and yogurt.

If you are not sure what kind of products you need to buy to get these fats, read our article about The Ketogenic Diet and Dairy in which we discuss how to buy the best quality dairy.

Bad fats during the ketogenic diet

One of the great aspects of the ketogenic diet is the ability to eat plenty of nutritious, satisfying fats as I described above.

However, it is also important to identify the types of fat that you want to limit or even completely avoid in your diet so as not to harm your health.

It is common to simply test and confirm whether you are in ketosis during a ketogenic diet, but the quality of your diet is still important.

Processed trans fats are best known to most people – and they can be very harmful to your health.

Artificial trans fats are formed during food production through the processing of polyunsaturated fats. For this reason, it is important to choose only multi-saturated fats that are unprocessed and not overheated or altered.

A good example of an oil that can be quite harmful after processing is rapeseed oil . The majority of this oil is obtained by a heating process (up to about 260 degrees Celsius) using hexanoic acid .

The result is that you buy a bottle with oxidized omega-3 and omega-6 fatty acids , or a source of inflammatory free radicals. 

The vegetable oils that you would rather avoid:

  • Soybean oil
  • Canola oil (rapeseed oil)
  • Corn oil
  • Grape seed oil
  • Peanut oil (peanut oil)
  • Sesame oil
  • sunflower oil
  • Safflower oil

An excess of these fatty acids stimulates the development of inflammation. In this way they form a breeding ground for various physical complaints. So avoid!

Omega 6 fatty acids fall under the polyunsaturated fatty acids. The best known of these fatty acids is linoleic acid which is common in vegetable oils such as sunflower and soybean oil. Other omega 6 fatty acids are arachidonic acid (AA) and gamma-linolenic acid (GLA).

Benefits of omega-6 fatty acids

Omega-6 fatty acids are not necessarily anti-inflammatory. Like omega-3 fatty acids, they can have a positive effect on health. The cholesterol level is lowered by fatty acids, which reduces the risk of cardiovascular disease.

If there is a shortage of linoleic acid in the body, symptoms such as growth retardation or dry skin occur.

The problem with contemporary food is that one gets too much omega-6, which is also heated and processed. These industrial vegetable oils cause inflammation in the body and can thus be the cause of chronic disorders.


Don’t be afraid of saturated fats, choose fats that are as unprocessed as possible and avoid fats and oils from processed, prepackaged foods made in a factory.

Ultimately, improving your health is the goal of the ketogenic diet – and that means not only ensuring a good ratio of fat, protein, and carbohydrates, but also choosing food sources that contribute to good health.

If you want to gain more insight into putting together a nutritious and balanced ketogenic diet, read our article on The Importance of a Nutritious Ketogenic Diet.

Also, use our Ultimate Ketogenic Nutrition List and our Ketogenic Avoidance List to discover which foods you should or should NOT use to follow a healthy ketogenic diet.

Fan of everything health and fitness related. My mission is to share my knowledge and experience with as many people as possible and help them to find their ideal path to perfect health.