What's the Difference Between Saturated Fat and Unsaturated Fat?

Do you remember the days when all fats were 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 fats!). It's now well-known that eliminating fat altogether is not the healthiest route. But some fats are more worthy (health-wise) than others.

We're going to give you a primer on each and teach you which ones are healthier. But first: there are three main types of fat—saturated, unsaturated and trans. Trans fats are predominantly man-made and are the worst health-wise; so much so that they've been banned in the U.S.

Then there are saturated fats and unsaturated fats. Here's the skinny (pun intended!) on those two.

What are saturated fats?

What differentiates the types of fat is how they're built (meaning their chemical structure), and then because of their chemical structure 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. 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

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., they're less saturated). Within the category of unsaturated fats, there are two main subcategories—monounsaturated fats and polyunsaturated fats. Both monounsaturated and polyunsaturated fats have heart-health benefits, though polys seem to have a slight edge over monos. Learn more about 4 foods to choose the full-fat versions over reduced-fat.

What foods are they in?

• Oils that are liquid at room temperature (i.e., vegetable, nut & seed oils)
• 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 organizations like the American Heart Association have recommended that for the sake of our heart health, we be mindful of—and limit—our saturated fat intake. That's because research over the years has suggested that limiting saturated fat consumption could lower your risk of cardiovascular disease (CVD). And about 1 in every 3 deaths in the U.S. is related to CVD.

A growing body of research, and some outspoken health experts and journalists, however, have more recently called into question just how bad saturated fat really is for your heart health. That debate is still not settled. But the final verdict on saturated fat and how bad it really is for you is somewhat irrelevant because saturated fat—when compared to unsaturated fat—will always be the less healthy one. Here's why:

• Many studies have found that people who eat more unsaturated fat and less saturated fat have lower rates of cardiovascular disease—as well as lower rates of other major causes of death. So, you see, it isn't just about heart health.
• Also, in studies where people replace some of their saturated fat with unsaturated fat (particularly polyunsaturated fat) their risk of cardiovascular disease diminishes significantly (about 30% per this AHA report). Some studies found this dietary shift to be as effective as taking a statin.
• Other research has shown that people who eat a lot of saturated fat eat less of other nutrients, like unsaturated fat and/or carbohydrates. In other words, more saturated fat in your diet could potentially edge out those known healthy unsaturated fats.
• One particular type of polyunsaturated fat—omega-3s—has ample science-backed health benefits. Research has shown omega-3s have potential brain- and heart-health benefits, as well as other anti-inflammatory properties that are beneficial for various conditions.

Bottom line

Overall, the Dietary Guidelines for Americans says you should limit your total fat intake to 25 to 35% of your daily calories. The recommended saturated fat cap is slightly more rigid: the Dietary Guidelines for Americans says less than 10% of your daily calories should come from saturated fat; the American Heart Association says cap it at 5 to 6% of your calories if you have high ("bad") LDL cholesterol. In case you're curious, the average American gets 11% of their calories from saturated fat.

Even though there is a limit on how much fat you should eat each day, that doesn't mean that less (or really a lot less) is better. Your body needs fat: not only is it 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.