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

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 a part of a balanced diet. To learn more about the difference between saturated and unsaturated fats and how we should integrate fats into our diet, we reached out to fellowship-trained nutrition and cognition physician Gabrielle Lyon, DO, 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 which fats are healthy for us. Keep scrolling to read what Gabrielle Lyon, DO, 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 and unsaturated fats?
GABRIELLE LYON, DO: Most people believe there are two types of fat (“good” and “bad”), but the truth is that there are degrees of both, and fat comes in three main forms, including 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.

Don’t believe the hype that saturated fats aren’t good for you. Despite decades of dietary recommendations against saturated fat, it is now well understood that saturated fats 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 healthy for us. They are needed for each of our cells to communicate with each other. They help cells function as signaling 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 overeating. How many of us have eaten that fat-free muffin only to be ravenous an hour later? The reason being that there were 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 everyone knows about the health benefits of fish and omega-3s. Well, those omega-3s are just half of the polyunsaturated fat puzzle. The omega-6s found in nuts and seeds are the other half.

Healthy Fats

BYRDIE: What are healthy fats?
GL: Healthy fats are any fat that is not hydrogenated or any polyunsaturated fat sold as “cooking oil” or margarine.

Healthy fats come from 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 get the health benefits. Saturated fats are used for heating and cooking purposes. Unsaturated fats are best used after cooking or in cold applications. 

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, which include avocado and avocado oil (cold pressed), hazelnut and macadamia nut butters and oils, olives, and cold-pressed extra-virgin olive oil. Second, saturated fats, which include grass-fed butter, clarified butter (ghee), coconut oil (be careful, as they are not all the same), and MCT oil. 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 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 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 mostly monounsaturated, and this is a good thing. Coconut oil is great choices for 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 for light sautéing. Extra-virgin olive oil is great, as it’s full of phytonutrients and antioxidants, but don’t waste it by overheating it.

4. Polyunsaturated for cold use. These oils are best as supplements. You can add some to your salad dressing or smoothie if you want to, but it’s not 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 delicate and will be damaged by heat, light, or air exposure. There is no good reason to buy vegetable oils that are sold for cooking.

5. Avoid hydrogenated fats outright. Check food labels diligently. Even if the product says “0g trans fats,” it still 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 meaningless. Look for the word “hydrogenated” on ingredients lists. If it’s there, the food is plastic. Don’t eat plastic.

6. 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 it 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 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. 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 anything processed.

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