Types of Fat: A Complete Guide To Fatty Acids

Last Updated on October 13, 2020 by Michael Joseph

One Stick of Butter In a Butter Dish With a Knife.There are so many different types of fat out there.

Unfortunately, many people experience a lot of confusion about dietary fat, mainly due to the mixed messages from the media.

Put simply; consumed sensibly, dietary fat is not a big dietary villain as once thought.

This article will take a look at the various varieties of fat, explain what they are and where to find them.

We will also review the different foods we can find these fats in.

Lastly, we will discuss which cooking oils are the most supportive of good health.

What Is Fat?

Alongside carbohydrate and protein, fat is one of the three macronutrients in our diet.

However, “fat” is not one single entity, and there are many different types – and subtypes – of fat.

Sometimes people refer to fats as “triglycerides,” which are the primary form of fat in our body and food. Triglycerides are comprised of glycerol and three different fatty acids.

Dietary fats have a wide range of biological functions, which we will discuss later.

Is Fat Essential For Humans?

Fat is essential for our health, but we do not have a biological need for all the different fatty acids.

The only essential fats are omega-3 and omega-6, and the reason for this is because our body cannot make them itself (1).

As a result, we need to consume omega-3 containing foods such as oily fish, and foods with omega-6, which is prevalent in everything from meat to nuts.

Since they are vital for our health, people often refer to omega-3 and omega-6 as essential fatty acids (EFA).

Key Point: Dietary fat is one of the three macronutrients and it plays an important role in our health. 

Types of Fat

There are four main classifications of fat that we can find in our food;

  • Saturated fat
  • Monounsaturated fat
  • Polyunsaturated fat
  • Trans fats

While you may have heard about “good fats” and “bad fats” before, this is an overly simplified definition.

In truth, there are some important considerations to understand.

Let’s quickly do an overview of each type of fat;

1) Saturated Fat (SFA)

A Diagram Showing the Molecular Structure - Carbon and Hydrogen Atoms - of Saturated Fat,

Saturated fatty acids are fully “saturated.”

To explain this, we first have to understand that fats are made from carbon (C), hydrogen (H) and oxygen (O).

First of all, saturated fat does not contain any double bonds.

For example, a carbon atom can connect to four different atoms – whether carbon (C) or hydrogen (H).

If a carbon atom connects to the next carbon atom in the chain twice (a double bond), then it will not be able to connect to all the hydrogen atoms it can.

Therefore, it will not be fully saturated.

As you can see in the image above, the carbon atoms only have a single bond to each other, and connect to hydrogen atoms. This is an example of saturated fat.

The molecules in saturated fats are packed close together, and the fat is solid at room temperature and very heat stable.

A List of Saturated Fatty Acids

Just as “fat” is not only one thing, neither is saturated fat.

Saturated fat comprises of a wide range of saturated fatty acids, which all have a different number of carbon atoms in their chain.

For this reason, some are known as ‘long-chain’ saturated fats and others are called ‘short-chain’.

Here are the saturated fatty acids alongside the number of carbon atoms they contain (in the lipid name column).

The ‘C’ refers to the number of carbon atoms, and the ‘0’ means there are no double bonds.

Fatty Acid Lipid Name Fatty Acid Lipid Name
Propionic acid C3:0 Butyric acid C4:0
Valeric acid C5:0 Caproic acid C6:0
Enanthic acid C7:0 Caprylic acid C8:0
Pelargonic acid C9:0 Capric acid C10:0
Undecylic acid C11:0 Lauric acid C12:0
Tridecylic acid C13:0 Myristic acid C14:0
Pentadecylic acid C15:0 Palmitic acid C16:0
Margaric acid C17:0 Stearic acid C18:0
Nonadecylic acid C19:0 Arachidic acid C20:0
Heneicosylic acid C21:0 Behenic acid C22:0
Tricosylic acid C23:0 Lignoceric acid C24:0
Pentacosylic acid C25:0 Cerotic acid C26:0
Heptacosylic acid C27:0 Montanic acid C28:0
Nonacosylic acid C29:0 Melissic acid C30:0
Henatriacontylic acid C31:0 Lacceroic acid C32:0
Psyllic acid C33:0 Geddic acid C34:0
Ceroplastic acid C35:0 Hexatriacontylic acid C36:0
Heptatriacontanoic acid C37:0 Octatriacontanoic acid C38:0

Notably, different saturated fatty acids occur in various proportions in different foods.

Furthermore, all saturated fatty acids have differing effects on our health.

Profiling each one is beyond the scope of this article, but it shows us why “good fats” and “bad fats” is far too simple.

Foods High In Saturated Fat

While many different foods contain saturated fat, it occurs in exceptionally high concentrations in dairy and tropical fats such as coconut oil.

Some further examples of saturated fat include the following foods;

  • Cocoa butter and chocolate
  • Dairy foods such as butter, cheese, cream, ghee and yogurt
  • Fish
  • Hydrogenated and partially hydrogenated (trans) fats
  • Meat
  • Nuts
  • Tropical fats like coconut and palm oil
Key Point: Saturated fat refers to a wide range of saturated fatty acids. This type of fat is very heat stable.

2) Monounsaturated Fat (MUFA)

Diagram Showing Molecular Structure of Monounsaturated Fatty Acids.

Monounsaturated fatty acids are a type of unsaturated fat which are liquid at room temperature.

In contrast to saturated fat, monounsaturated fat contains a single double bond between two carbon atoms, as shown in the above image with two lines connecting the ‘C’ atoms.

The presence of this double bond means that monounsaturated fat is not fully saturated with hydrogen atoms, and it is slightly less heat stable than saturated fat.

However, saturation is not the only consideration that determines the oxidative stability of cooking fat.

For instance, phytonutrients/polyphenols in fat can help to prevent oxidative damage and the oil from breaking down (2, 3).

This fact is one reason why extra virgin olive oil, complete with all its polyphenols, is much more heat stable than heavily refined olive oils, which are lower in these compounds.

A List of Monounsaturated Fatty Acids

Similar to saturated fat, there is a wide range of monounsaturated fatty acids too.

The most prevalent of these is called oleic acid, which is actually the most commonly occurring fatty acid in nature.

Oleic acid is also the predominant fatty acid in avocados and olive oil, as well as most kinds of meat.

The table below shows the full range of monounsaturated fatty acids.

The ‘lipid name’ column shows the number of carbon atoms followed by the number of double bonds; carbon atoms:double bonds.

The ‘n-‘ number denotes the location of the double bond.

Fatty Acid Lipid Name Fatty Acid Lipid Name
Myristoleic acid C14:1 (n-5) Palmitoleic acid C16:1 (n-7)
cis-Vaccenic acid C18:1 (n-7) Vaccenic acid C18:1 (n-7)
Paullinic acid C20:0 (n-7) Oleic acid C18:1 (n-9)
Elaidicacid (trans-oleic) C18:1 (n-9) Gondoic acid C20:1 (n-9)
Erucic acid C22:1 (n-9) Brassidic acid C22:1 (n-9)
Nervonic acid C24:1 (n-9) Sapienic acid C16:1 (n-10)
Gadoleic acid C20:1 (n-11) Petroselinic acid C18:1 (n-12)

It is interesting that most people think of meat as saturated fat.

For one thing, monounsaturated fat is the predominant fat in many types of meat and animal fats in general.

For example, lard contains 45% monounsaturated fatty acids and 39% saturated fatty acids (4).

The delicious ribeye steak also contains slightly more monounsaturated fat (5).

This fact is quite interesting because there is a common myth that only saturated fats are heat stable, which is something that many animal fat proponents promote.

Monounsaturated fats are not quite as heat stable as saturated fat, but they are a lot more stable than polyunsaturated fatty acids, which is the next type of fat we will discuss.

Foods High in Monounsaturated Fat

The primary dietary sources of monounsaturated fat include the following foods;

  • Avocados
  • Fish
  • Meat
  • Nuts (especially macadamia)
  • Olives and olive oil
  • Seeds
Key Point: Monounsaturated fatty acids contain one double bond, they are liquid at room temperature, and they are reasonably heat stable. This is particularly the case for fats that contain polyphenolic compounds such as extra virgin olive oil.

3) Polyunsaturated Fat (PUFA)

Diagram Showing the Molecular Structure of Polyunsaturated Fatty Acids.

Polyunsaturated fats are another type of unsaturated fat.

However, unlike monounsaturated fat, polyunsaturated fatty acids have multiple double bonds in their structure.

As you can see in the image, there are numerous double bonds between the carbon atoms.

For this reason, polyunsaturated fat is the least stable, and it can readily oxidize at high heat.

Polyunsaturated fatty acids are also liquid at room temperature.

There are three different types of polyunsaturated fat, and these include omega-3 and omega-6 fatty acids, and one omega-9 fat.

You may see the full range of polyunsaturated fats in the table below;

Fatty Acid Lipid Name Type of Fat
Hexadecatrienoic acid C16:3 (n-3) Omega-3
Alpha-linolenic acid C18:3 (n-3) Omega-3
Stearidonic acid C18:4 (n-3) Omega-3
Eicosatrienoic acid C20:3 (n-3) Omega-3
Eicosatetraenoic acid C20:4 (n-3) Omega-3
Eicosapentaenoic acid C20:5 (n-3) Omega-3
Heneicosapentaenoic acid C21:5 (n-3) Omega-3
Docosapentaenoic acid C22:5 (n-3) Omega-3
Docosahexaenoic acid C22:6 (n-3) Omega-3
Tetracosapentaenoic acid C24:5 (n-3) Omega-3
Tetracosahexaenoic acid C24:6 (n-3) Omega-3
Linoleic acid C18:2 (n-6) Omega-6
Gamma-linolenic acid C18:3 (n-6) Omega-6
Eicosadienoic acid C20:2 (n-6) Omega-6
Dihomo-gamma-linolenic acid C20:3 (n-6) Omega-6
Arachidonic acid C20:4 (n-6) Omega-6
Docosadienoic acid C22:2 (n-6) Omega-6
Adrenic acid C22:4 (n-6) Omega-6
Docosapentaenoic acid C22:5 (n-6) Omega-6
Tetracosatraenoic acid C24:4 (n-6) Omega-6
Tetracosapentaenoic acid C24:5 (n-6) Omega-6
Mead acid C20:3 (n-9) Omega-9

Omega-3

The Molecular Structure For Docosahexaenoic Acid (DHA)

Omega-3 fats play a vital role in our overall health.

There are two primary omega-3 fatty acids; eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). These occur naturally in animal foods.

Additionally, another omega-3 fatty acid – alpha-linolenic acid (ALA) can be found in various plant foods.

Importantly, omega-3’s are anti-inflammatory and systematic reviews and randomized controlled trials show that they help to (6, 7, 8);

  • Reduce blood pressure
  • Improve overall cardiovascular health.
  • Improve the lipid (cholesterol) profile by lowering triglycerides and raising HDL.
  • Help to protect against cognitive impairment and dementia/Alzheimer’s.

Foods High in Omega-3 Fatty Acids

Fish and seafood are the best sources of omega-3.

The list below shows common sources of these fatty acids;

  • Oily fish such as anchovies, herring, mackerel, salmon, sardines and trout.
  • Eggs, meat and milk from animals raised on fresh pasture (especially lamb meat.)
  • Fish roe
  • Oysters and other shellfish
  • Green leafy vegetables*
  • Nuts (especially walnuts)*

* Note that animal foods are the best source of omega-3 since they provide preformed EPA and DHA.

While plant foods also contain omega-3 fatty acids, they are in the form of ALA, which is not bioavailable and requires conversion to EPA and DHA inside the body.

Unfortunately, conversion rates are unreliable and can be as low as 0-4% (9).

Generally, we aren’t getting enough omega-3, and we should look to increase our consumption of omega-3 fatty acids.

See this full guide to omega-3 fats for more information.

Key Point: Omega-3 fatty acids are anti-inflammatory in nature, and they are a type of polyunsaturated fat. Ensuring sufficient intake of these fatty acids may provide some important benefits.

Omega-6

Diagram Showing the Molecular Structure For Omega-6 Linoleic Acid.

Omega-6 is also an essential fat, meaning that we need to acquire sufficient amounts of this fatty acid from food.

Omega-6 fatty acids play an important role in normal growth and development, and they are vital for brain function (10).

When discussing omega-3 and omega-6, a common topic that arises is how the ratio of these two fatty acids may affect health.

For instance, some researchers claim that traditional human diets had an omega-6 to 3 ratio close to 1:1. Conversely, the modern American diet can be as high as 20:1, which some people claim may lead to an increased risk of damage from inflammatory processes (11, 12, 13).

But is this something we should actually worry about?

See this guide on the omega-6 to 3 ratio and whether it matters for more information.

Foods High in Omega-6 Fatty Acids

The following list shows foods high in omega-6.

However, most people are consuming large amounts of omega-6 now, and the fat is present in almost all foods.

Due to this, there is no real reason to seek out foods high in the fat specifically as most people already get enough.

  • Fatty cuts of chicken and pork (particularly grain-fed animals)
  • Mayonnaise
  • Nuts
  • Potato chips
  • Salad dressings
  • Seeds
  • Snacks made with vegetable oils
  • Vegetable (seed) oils such as corn, grapeseed and soybean oil.
Key Point: Omega-6 is an essential fat, but most people are consuming too much of it these days.

4) Trans Fats

Picture of a Crisco Container - Artificial Cooking Fat Containing Trans Fats.

Trans fats can be either natural or man-made in origin.

A type of trans-fatty acid occurs naturally in animal foods called conjugated linoleic acid, and this fatty acid may have some positive health benefits (14).

However, artificial man-made trans fats are a different matter. Trans fats are unsaturated fatty acids (often cottonseed or soybean oil) that undergo a hydrogenation process to make them appear like saturated fat.

Some examples of trans fats include vegetable shortening and margarine, which are both solid in texture.

Initially, researchers saw potential benefits from this hydrogenation process such as better shelf-life and more stability at high heat. However, the problem is that these artificial fats were so different from anything in nature that our body did not know what to do with them.

In short; the molecular structures are arranged differently and they appear foreign to our body. As a result, they are unstable, they can readily oxidize, and they can potentially lead to a number of health problems (15, 16, 17).

In fact, industrial trans fats are associated with health conditions such as insulin resistance, type 2 diabetes, cardiovascular heart disease, and cancer (18, 19, 20).

Foods High in Trans Fatty Acids

It is hard to know which foods contain trans fats without looking at an ingredients label, but many of the following foods may contain trans fat;

  • Biscuits/cookies
  • Cakes
  • Crackers
  • Deep-fried foods
  • Frozen foods/ready meals
  • Margarine
  • Non-dairy coffee creamers
  • Peanut butter
  • Pies and pastries

Fortunately, if we focus on fresh and healthy whole foods we can avoid trans fats without having to think about it.

If you buy packaged foods, give the label a quick scan for any mentions of ‘partially hydrogenated’.

Key Point: Trans fats are an industrial product and one of the worst things we can possibly eat. Avoid this type of fat.

Final Thoughts

Dietary fat can affect our health in many ways, and it can either be beneficial or detrimental depending on the type (and quantity) of fat.

Fat also helps our body to absorb fat-soluble vitamins and it makes our food taste delicious too.

All in all, fat isn’t “bad” for us as many have been led to believe over recent decades.

But that doesn’t mean that it can’t be bad; as with anything, the dose makes the poison.

To learn more about different nutrients, see this list of nutritional topics.

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Wendy Ellis
Wendy Ellis
2 years ago

Thankyou, an interesting article.