Saturated Fat & Unsaturated Fat: What's the Difference?

It's hard to believe there was a time when everyone thought all fat was bad. That's right—a few decades ago, it didn't matter what type of fat you were referring to because they were all nearly verboten. No surprise, times have changed. Today, there are some fats that we're told to eat multiple times a week (hello, omega-3 fatty acids!). It's now well-known that eliminating fat is not the healthiest route. However, some fats should play a more prominent role in the diet.

We will give you a primer on the main types of dietary fats and teach you which ones to focus on. But first, let's review—there are three main types of dietary fat: saturated, unsaturated and trans fat. Trans fats are predominantly man-made, but you'll find small amounts of trans fat in naturally occurring sources, such as meat and dairy. In 2023 the Food and Drug Administration gave the final ruling for man-made trans fat—often seen in ingredient lists as partially hydrogenated oils—to be banned from food in the United States.

So, that leaves us with saturated fats and unsaturated fats to focus on. Here's the scoop.

What Are Saturated Fats? 

What differentiates the types of fat is how they're built (meaning their chemical structure), and because of this, they function differently in our bodies.

All fats are built of carbons and hydrogens. Saturated fats are chains of carbon atoms with as many hydrogen atoms on that chain as possible. The carbons are, literally, saturated with hydrogen atoms. Because those carbon chains are so full with hydrogen atoms, the chains are stiffer, less flexible. This is why saturated fats are solid at room temperature (think: butter, the white fat on a cut of red meat, etc.).

What Foods Are They In? 

• Butter
• Ghee
• Lard
• Oils that are solid at room temperature, like coconut oil
• Whole milk & other full-fat dairy products
• Cheese
• Red meat & processed red meats
• Baked goods

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What Are Unsaturated Fats? 

Unsaturated fats are liquid at room temperature (not solid like saturated varieties). Structurally, they don't have as many hydrogen atoms bonded to carbon atoms (i.e., the carbon chain is less saturated), distinguishing them from saturated fats. Here's where the science gets cool. If the carbon chain has one double bond, it's a monounsaturated fat. If it has multiple double bonds along the carbon chain, it is a polyunsaturated fat—the two main types of unsaturated fats.

There are two essential types of polyunsaturated fats: omega-6 and omega-3 fatty acids. The number of polyunsaturated fats indicates where the double bond is located on the carbon chain; for example, in omega-3 fatty acids, the double bond happens at the third carbon. Omega-9 fatty acids are a type of monounsaturated fat that occur naturally in the body and are found in foods such as olive oil and avocados.

Okay, now that you're going to ace the organic chemistry round of your next trivia night, here's what you need to know about how they impact your health. Both monounsaturated and polyunsaturated fats have heart-health benefits, though polys seem to have a slight edge over monos.

What Foods Are They In? 

• Oils that are liquid at room temperature (i.e., olive oil, canola oil, grapeseed oil)
• Nuts
• Seeds
• Fatty, oily fish, such as salmon, tuna, trout, etc.
• Avocado

Which Fats Are Healthier: Saturated or Unsaturated Fats? 

For nearly six decades, health experts and public health organizations have recommended that for the sake of our heart health, we should be mindful of—and limit—our saturated fat intake. The recommendation is that no more than 6% of calories should come from saturated fat, according to the American Heart Association (AHA). That's because research over the years has suggested that limiting saturated fat consumption could lower your risk of cardiovascular disease (CVD). And about one in every five deaths in the U.S. is related to CVD, according to the Centers for Disease Control and Prevention.

A growing body of research and some outspoken health experts and journalists, however, have more recently called into question the current saturated fat recommendation and impact on heart health, according to a 2023 review. They argue that the relationship between saturated fat intake and cardiovascular disease might be more complex than previously understood, suggesting the need for a re-evaluation of dietary guidelines based on evolving scientific evidence.

The debate may not be settled soon, which means there is no final verdict from the experts. But in one consensus scientific statement, a shift to eating more unsaturated fats versus saturated fats is associated with better cardiovascular health.

Some studies have shown that when people replace the saturated fat in the diet with unsaturated fat (particularly polyunsaturated fat), their risk of cardiovascular disease decreases; however, not all studies have shown this association.

Research has firmly concluded that the rising consumption of ultra-processed foods has led to an increased risk of cardiovascular disease, type 2 diabetes and obesity. These types of foods often contain higher levels of saturated fats, added sugars and excess sodium. Consuming them more frequently may reduce the intake of more nutritious options, such as foods rich in unsaturated fats, fiber, protein and antioxidants, which are essential for supporting overall health.

Our Expert Take 

Overall, the 2020-2025 Dietary Guidelines for Americans recommends a total fat intake of 25% to 35% of your daily calories, with no more than 10% from saturated fat, slightly more than the AHA recommendation. Even though there is a limit on how much fat you should eat each day, that doesn't mean that less is better. Your body needs fat—not only as a source of energy to keep us moving through life, but fat also plays a key role in essential body functions, and without it your body can't absorb some vitamins and minerals. As with most nutrition advice, though, moderation reigns supreme.