The Difference Between Saturated and Unsaturated Fats (and Why It's Important)

Dacy Knight

For a long time, fats have gotten a bad rap. Many a fad diet has called for avoiding certain kinds of fats or cutting fats entirely. But with a greater scientific understanding—and eating plans like the ketogenic diet gaining in popularity—our perception of fats is changing and there's more and more reason to believe that healthy fats are part of a balanced diet. To learn more about the difference between saturated and unsaturated fats and how we should be integrated fats into our diet, we reached out to fellowship-trained nutrition and cognition physician Dr. Gabrielle Lyon, who splits her time between The Ash Center for Comprehensive Medicine in New York and Four Moons Spa, a new modern space for wellness in San Diego. She walked us through each type of fat and outlined exactly what fats are healthy for us. Keep scrolling to read what Dr. Gabrielle Lyon has to say about the difference between saturated and unsaturated fats, plus her fat consumption rules.

Saturated vs. Unsaturated Fats

BYRDIE: What is the difference between saturated fats and unsaturated fats?

DR. GABRIELLE LYON: Most people believe there are two types of fat “good” and “bad” but the truth is there are degrees of both, and fat comes in three main forms. Saturated, Monounsaturated, and Polyunsaturated. Let’s get technical for one quick minute. Saturated fats contain no double bonds. Each carbon has two hydrogens. The chain is “saturated” with hydrogens. Unsaturated fats, on the other hand, have one or more double bonds between the carbons. OK that’s it for the chemistry lesson now to the info you really want to know.

Don’t believe the hype saturated fats aren't actually good for you. Despite decades of dietary recommendations against saturated fat, it is now well understood that saturated fats actually promote health. It’s the man-made “saturated” fats called hydrogenated and partially hydrogenated fats that have contributed to our fear of fats.

Natural saturated fats are actually healthy for us. They are needed for each of our cells to communicate with each other. They help cells function as signalling messengers for hormone production. Without them our brain can’t function properly. Our needs them to process that nice glass (or two) of wine we have to relax after work or putting the kids to bed. Our heart needs it to produce the energy it needs to keep us alive. Saturated fats help our immune system and assimilate fat soluble nutrients like vitamin D,E,K, and A. Saturated fats also help trigger the satiety hormone that keeps us from over eating. How many of us have eaten that fat free muffin only to be ravenous an hour later, Why? No healthy fats to tell our body we have all the energy we need.

Unsaturated fats come in two main forms, Monounsaturated and polyunsaturated. Most of us have heard of the Mediterranean diet and how it is healthy because of all the monounsaturated olive oil that is in it. And of course, there is not a soul alive that hasn’t been told about the health benefits of fish and its Omega-3’s. Well those Omega-3’s is just half of the polyunsaturated fat puzzle. Omega-6 found in nuts and seeds are the other half.

Healthy Fats

BYRDIE: What are healthy fats?

GL: Healthy fats are most any fat that is NOT hydrogenated or any Polyunsaturated fat sold as “cooking Oil”, or margarines.

Healthy fats come in all sorts from the well-known olive oils and fish oils to the more controversial coconut and grass-fed butter. Knowing how to use each type of fat is also important to fully get the health benefits from fat. Saturated fats are used for heating/cooking purposes. Unsaturated fats are best used after cooking or in cold applications. Let me use extra virgin olive oil (EVOO) as an example. We all go and some of us even pride ourselves in the fact that we buy and use only the best most expensive EVOO. What we have to remember is that what we are buying is the first pressed most unrefined RAW form of olive oil there is. Great, now we take that same expensive RAW olive oil and put it into a hot pan! Does that make sense? Let’s always remember each type of oil has applications it is best suited for.

BYRDIE: What are some of your top food recommendations for healthy fats?

GL: When it comes to the foods for healthy fats, I like to break that down into three areas. First, Monounsaturated fats and they include: Avocado and avocado oil (cold pressed), Hazelnut, Macadamia nut butters and oils, Olives and cold pressed extra virgin olive oil. Second, Saturated fats, Grass-fed butter, clarified butter (ghee), Coconut oil (be careful they are not all the same) and MCT oil. And third polyunsaturated fats should be used sparingly and they include: almond butter and oil, brazil nuts, cashews and cashew butter, pecans and pistachios.

Fat Consumption Rules

BYRDIE: How much fat should someone aim to consume in their diet?

GL: The amount of fat in your diet will vary from person to person and the “type” of diet they are following. A very good rule of thumb for most people is to keep their fat intake to about 30% of the total calories each day. 

BYRDIE: What are some common misconceptions about saturated and unsaturated fats or fats in general?

GL: I think this question is best answered by what I call the “The Fat Intake Rules”:

1. Eat enough fat. The proper amount is not going to make you fat, clog your arteries or give you cancer. The reason fat tastes so good is because your body needs it. Give your body what it needs.

2. Cook with saturated fats. They are the most heat-stable and will be relatively undamaged even with high-heat applications. Animal fats like lard and duck fat are actually mostly monounsaturated, this is a good thing. Coconut oil is great choices for all you vegetarians.

3. Monounsaturated for cold to low heat. Use these oils from vegetable sources for cold applications like salads, low heat applications like pouring over hot vegetables or, if you like, for light sautéing. Extra virgin olive oil is great, full of phytonutrients and antioxidants, but don't waste it by overheating it.

4. Polyunsaturated for cold use. These oils are really best as supplements. You can add some to your salad dressing or smoothie if you want to, but it's not really necessary. Take your fish oil or flax oil as a supplement and get the rest of these important fats from your diet. Never heat polyunsaturated oils. Yes, they are sold as cooking oils in the supermarket but these oils are very delicate and will be damaged by heat or by light or air exposure. There is no good reason to buy vegetable oils that are sold for cooking. 

5A. Avoid hydrogenated fats outright. Check food labels diligently. Even if the product says "0g trans fats," it still, by law, can contain up to 0.5 grams per serving. Considering the fact that food processors can designate serving size any way they like, these numbers are truly meaningless. Look for the word "hydrogenated" on ingredients lists. If it's there, this food is plastic. Don't eat plastic.

5B. Skip spreads. Since saturated fats are not harmful, there's no reason to buy processed vegetable spreads that employ different tricks to imitate the properties of the real stuff. Hydrogenation, interesterification, and the use of thickeners and blending fats and oils are all employed to make something inherently un-spreadable into something apparently spreadable. Just go for the real thing - butter. Better yet, boil the butter to make it into 'ghee' - it's more stable, is free of dairy proteins and lasts outside of the fridge for months. 

To sum it all up, names are more for convenience. Remember that no fat is entirely saturated, monounsaturated, or polyunsaturated. Every fat source is a mixed bag of all these types. We refer to animal fats as "saturated" and vegetable oils as "polyunsaturated" as a kind of shorthand. But many animal fats actually have more monounsaturated than saturated fats. Even olive oil contains some saturated fat and you can get omega-3s from butter. Remember not to take these labels as gospel. Good fat is good, bad fat is bad. There is still the need to be vigilant in what we eat, including avoidance of over-processed, nutrient-depleted faux foods and meat and dairy from sick animals. Choose fresh, choose organic choose 100% pasture raised and choose local. Avoid processed anything.

Learn about the healthy fats nutritionists agree belong in your diet. 

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