All About Fats – Part 1: What Are They

Fats

A fat molecule, more formally known as triglyceride, is made up of a glycerol molecule and three (tri) fatty acid molecules. Fatty acids have a head made of carbon, hydrogen and two oxygen molecules. The tail is made up of repeating sequences of carbon and hydrogen. The carbon atoms line up in a zig-zag formation and hydrogen atoms (not shown in images) are attached to the carbon atoms. The tails can vary in length and structure, which allows for a wide variety of fat molecules.


The fatty acids on a fat molecule can come in three types: Saturated, Monounsaturated and Polyunsaturated. The unsaturated fats can come in two different configurations: Cis and Trans. The type of fat and the configuration can have a significant impact on the fat molecule’s shape. Mono and polyunsaturated fats have a double bond between two carbon atoms on the fatty acids that causes the molecule to bend at that point. A double bond means that the two carbon atoms share two pairs of electrons instead of just one. Unlike saturated fats, which only have more stable single bonds, double bonds provide a suitable place for chemical reactions to occur.

Monounsaturated fats have one double bond whereas polyunsaturated fats have two or more double bonds. Saturated fats have no double bonds between carbon atoms and are saturated with hydrogen atoms. The double bonds make unsaturated fats more likely to react with oxygen or other reactive compounds. This is why unsaturated fats can go rancid faster than saturated fats.
 

The Types of fats

 

 

Arachidic acid – A Saturated fat

Saturated Fats

Saturated fats are fats that have no double bonds between their carbon atoms so they are saturated with hydrogen atoms. In this form, the fatty acid is relatively stable. This means that the molecule is less likely to react with other atoms or molecules and break down. It also has a uniform shape and charge that allows them to “stick” to other saturated fats. This stickiness causes them to be solid at room temperature. Only when the temperature is raised, usually above body temperature, (with some exceptions) will these fats become liquid. Example: Fat from a hamburger coming off a grill is a clear liquid. As that liquid cools down, it becomes a solid white fat.
 

Oleic acid – A monounsaturated fat

Monounsaturated Fats

Monounsaturated fats contain one double bond between two carbon atoms. The double bond prevents the atoms there from rotating freely like the rest of carbon atoms that are single bonded. As a result, it causes the fatty acid to bend at that point. Notice that the image of oleic acid above has one bend in it.
 

Eicosapentaenoic acid (EPA) – A polyunsaturated fat

Polyunsaturated Fats

These fats have two or more double bonds in the fatty acid chain that causes the molecule to bend multiple times. EPA in the image above is a polyunsaturated fatty acid found in fish oil that contains multiple bends along its’ body.

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Omega Fats

Omega fats are polyunsaturated fatty acids. The omega refers to the first double bond that happens starting from the end of the fatty acid tail. For example, omega 3 fats have the first double bond occurring at the 3rd carbon from the end of the tail. Omega 6 fats have the first double bond at the 6th carbon from the tail.

DHA is an omega 3 fatty acid found in fish oil. Notice how the first double bond in the fatty acid occurs at the 3rd carbon from the omega (w) end. This is where the first bend in the molecule occurs.