Saturated Fats vs. Unsaturated What’s the Difference? Which to Choose?

Saturated Fats vs. Unsaturated What’s the Difference? Which to Choose?

Video | What are Fatty Acids? | Cooking with Fats | Takeaway

The fats you eat are either saturated or unsaturated. In this post, I’ll explain the difference, tell you the foods that contain each type, and share which fats I use in my kitchen.

Saturated Fats vs. Unsaturated Fats At-A-Glance

  • Whether a fatty acid is saturated or unsaturated is determined by how the carbon atoms are bonded together.
  • Saturated fatty acids have only single bonds between the carbons, which makes them stable molecules.
  • Unsaturated fatty acids have one or more double bonds, which make them unstable when exposed to elements like heat and oxygen.

Saturated Fats vs. Unsaturated Fats [Video]

In this video, you’ll learn…

  • The difference between saturated fat and unsaturated fat.
  • The composition of different fat molecules.
  • Which fats are best for cooking!

Why Do We Call Them Fatty Acids?

The fats that you eat contain fatty acids. A fatty acid molecule is a string of carbons with hydrogen atoms around them, and a compound at one end called a carboxyl group. That carboxyl group is what makes it an acid and is why we call them fatty acids. 

saturated fat molecule

Saturated Fatty Acids vs Unsaturated Fatty Acids 

What makes a fatty acid saturated or unsaturated is determined by how the carbon atoms are bonded together.

Saturated fatty acids have only single bonds between the carbons.

Saturated Fatty Acid

Whereas, unsaturated fatty acids have one or more double bonds. If there are at least two double bonds, it is a polyunsaturated fat. 

polyunsaturated fatty acid

If there is just one double bond, it is a monounsaturated fat.

monounsaturated fatty acid

What a Difference a Bond Makes!

The differences in bonding that we see with saturated vs. unsaturated fats may seem like a small thing. However, these single and double bonds have significance as to whether or not we can safely use the fat in our diet.

Saturated fats are solid fat

If we look at a saturated fat molecule, we see that it only contains single bonds between the carbon atoms. That makes this molecule nice and straight. Therefore, saturated fats can fit closely together with their neighboring fatty acid, making it a solid fat. 

Saturated fat molecules are straight

A perfect example is this solid fat is a stick of butter, which is mostly composed of saturated fat. 

Saturated fats are also found in other animal products. Examples include eggs, full-fat dairy products (cheese, cream, milk), and red meat. Tropical oils, like coconut oil and palm oil, also contain saturated fatty acids. 

Unsaturated fats are liquid

When we look at an unsaturated fat molecule, we see that the double bonds cause the molecule to bend or kink. Unsaturated fats, therefore, don’t fit together as snuggly and what we get is an oil or liquid fat.

unsaturated fats bend due to double bonds

Examples of unsaturated fats include olive oil and avocado oil, which are composed mainly of monounsaturated fats. Vegetable oils like soybean, corn, and canola oils, contain mostly polyunsaturated fatty acids. 

Cooking with Fats

The double bonds in the unsaturated fats expose a vulnerability and make vegetable oils unstable when exposed to heat or air. For this reason, I don’t recommend using polyunsaturated vegetable oils in any capacity, especially as cooking oils

Monounsaturated oils can be used for non-cooking purposes, like making salad dressing. However, I do not use olive oil for cooking because it has a lower smoke point than avocado oil, which is an oil I feel comfortable using for cooking. 

Saturated Fats and Cooking

Saturated fats are more stable than unsaturated fats when exposed to elements like heat. 

If you look at the carbon atoms of a saturated fat, the first thing you notice is that each carbon has four hands. Two of those hands are attached to hydrogen atoms and two are shaking hands with neighboring carbons. 

single bonds of saturated fatty acids

In other words, the carbon bonds in a saturated fatty acid are saturated. There is no available bond that is free to grab hold of a new atom. Therefore, this molecule is not going to react with things like hydrogen or oxygen atoms, remaining stable during cooking.

Unsaturated Fats and Cooking

If you look at the carbon atoms of an unsaturated fat, you see that some of the carbons have double handshakes going on. In other words, they are double bonded to each other.

double bonds of unsaturated fatty acids

This double handshake is awkward. You don’t walk up to someone on the street and shake both of their hands. Those double-bonded carbons are “unstable.” They are looking for an oxygen or hydrogen atom to grab hold of, which is not what you want to happen. 

Because vegetable oils oxidize (i.e., react with oxygen) easily, they produce oxidation products like free radicals that damage your cells. 

The unsaturated fats can also be exposed to hydrogen in a lab setting through a process called hydrogenation. This is the process that allows food manufacturers to turn a liquid vegetable oil into a solid, like Crisco or Margarine.

The unfortunate side-effect of hydrogenation is that it creates trans fats, which are certainly a well-documented health hazard. 


Does this mean that saturated fats are healthier than vegetable oils? There is a growing body of research showing that vegetable oils are not what we want to be using in fast food fryers or any cooking for that matter because of how they react when heated. If you are interested in the full story, I recommend Nina Teicholz book, The Big Fat Surprise.

Monounsaturated fats only contain one double bond and are therefore more stable than polyunsaturated fats when exposed to heat or air. However, nothing compares to the stability of saturated fats. 

I will leave you with one final thought. In preparation for this post, I spoke with my 99-year-old grandmother. I asked her what fats she cooked with when she was young. She shared that she started her married life using lard and then switched to butter. Both are saturated fats. While this is far from proof that saturated fats are safe, it does make you think :).

Thank you for reading and have a wonderful week!

About the Author:

Dr. Becky Gillaspy, DC graduated Summa Cum Laude with research honors from Palmer College of Chiropractic in 1991.

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