Dietary fat is back. As recently as the 1990s, this nutrient was vilified in popular culture, and healthcare professionals set guidelines aimed at decreasing fat intake to encourage Americans to lose weight, according to an article published in August 2017 in Nutrition Journal. Today, in light of newer research, the recommendations on fat intake are more nuanced, with some types being praised and others sworn off for optimal health.

The continued popularity of the ketogenic, or “keto,” diet, which is a high-fat and very low-carbohydrate diet, takes this new embrace of fat to the extreme. On this diet, followers strive to get 75 percent of their calories from fat, 20 percent from protein, and 5 percent from carbs, though other versions of keto mandate different ratios. So fat is no longer feared — in the case of keto, it’s celebrated.

That said, outside of keto, there’s such a thing as too much fat, or any food for that matter. A review published in April 2019 in the Journal of Diabetes Mellitus and Metabolic Syndrome notes that eating too much dietary fat can lead to weight gain.

Here’s your guide to the different types of fat, how to spot healthy sources of fat, and what to know about incorporating more of this macronutrient in your diet.

Why Are Dietary Fats Important?

“Dietary fats are essential to give your body energy and to support cell growth. They also help protect your organs and help keep your body warm,” says Julene Stassou, RD, author of The Mediterranean Diet Weight Loss Solution, who is based in Englewood Cliffs, New Jersey.

What’s more, she says, fats also improve the absorption of fat-soluble nutrients in your body (like vitamins A, E, D, and K) and play an important role in hormonal health. The recommended intake of fat for most Americans is 20 to 35 percent of daily calories, according to the National Academies of Sciences.

Types of Fat

While it’s important to include fat in your diet, it’s also critical to choose the right kinds of fat. Some types of fat can be dangerous, while others, in moderation, can promote health.

There are three main categories of fats: saturated, unsaturated, and trans. Here is what you need to know about each.

Saturated Fat

These fats are solid at room temperature. A higher intake is linked to a higher LDL (“bad”) cholesterol level, which can increase the risk for heart disease. Saturated fats should be limited as much as possible, but it’s not possible to completely omit them from your diet. That’s because foods contain a mixture of both saturated and unsaturated fat, points out the National Academies of Sciences. Some foods have a greater proportion of saturated fat, while some have a greater proportion of unsaturated fat. Saturated-fat-rich foods include fatty cuts of meat, bacon, butter, whole-milk dairy, and coconut oil.

Unsaturated Fat

These are liquid at room temperature and are found in plant foods. “They are different from saturated fats because they contain one or more double bonds and fewer hydrogen atoms on their carbon chains,” says Stassou. Essentially, this means they are simply less saturated (with hydrogen molecules).

Unsaturated fats can be broken up into monounsaturated fats and polyunsaturated fats, which is a chemical term that signals if they’ve been saturated once (monounsaturated) or more than once (polyunsaturated), says Jill Weisenberger, RDN, CDCES, author of Prediabetes: A Complete Guide, who is based in Yorktown, Virginia. “Both are good for us, and you don’t have to get too worked up over which [of the fats you’re eating] are monos or polys. When you decrease some of [your] saturated fats and replace them with unsaturated fats, you can decrease your risk for heart disease, [have] better insulin sensitivity and cholesterol levels, and reduce inflammation,” she says.

Trans Fat

The Food and Drug Administration (FDA) has taken steps to remove artificial trans fats in processed foods, as these are known to significantly raise levels of LDL cholesterol, which can increase your risk for heart disease.

Trans fat is found naturally in some animal sources, like milk, butter, cheese, and meat. It can also be made during manufacturing when hydrogen is added to vegetable oil, a process that turns liquid fat into a more stable solid at room temperature, says the FDA. This is artificial trans fat (called hydrogenated or partially hydrogenated), a type of fat that you should avoid, says Stassou.

While the FDA has called for a removal of these artificial trans fats from food, trans fat could still be found in fried foods, margarine, vegetable shortening, baked goods, and processed snack foods, says Stassou.

The Healthiest and Least Healthy Sources of Fat

Fats are often spoken about as “good” or “bad,” but really, they can be grouped into “eat more of” and “limit.” “We speak about fats differently now than we used to,” says Sandra Meyerowitz, MPH, RD, owner of Nutrition Works in Louisville, Kentucky. “They all used to be clumped together, and now we separate them out. We steer clear of the saturated and the trans fats, which are unhealthy, and lean toward [unsaturated fats].”

Healthy Fats

Fats you should eat more of are available in these food sources:

Fish and other seafood, especially salmon and other fatty fish
Nuts, including walnuts, pecans, and almonds
Flaxseed oil
Vegetable oils, like canola, olive, soybean, corn, avocado, sunflower, and safflower
Sesame, pumpkin, chia, flax, and other seeds
Avocados

Hacks for Incorporating More Healthy Fats Into Your Diet

Recommendations for ensuring adequate daily fat intake pertain to sources of healthy fat. Healthcare professionals, in other words, are not advocating eating more processed foods, fried foods, or desserts. Instead, focus on cooking with healthy fats and eating foods that are rich in unsaturated fats.

Here are four ways to get more healthy fats into your diet:

Cook with liquid oils. Rather than cooking with semihard fats like coconut oil, butter, or lard, go for liquid oils, including canola, olive, or avocado, says Weisenberger.
Switch up your snacks. Instead of eating chips or crackers, snack on nuts like almonds, walnuts, or pistachios, says Stassou. Dunk vegetable slices into guacamole or spread almond butter on an apple.
Top soups and salads with healthy fats. When you finish making lunch or dinner, think: Did I use a healthy fat in this? If not, that’s when you can add olives, nuts, seeds, or sliced avocado on top of salads, soups, or chili, suggests Stassou.
Plan a fish night. Fatty fish like salmon, albacore tuna, sardines, lake trout, and mackerel are rich in omega-3 fatty acids, a polyunsaturated fat that’s also good for your heart, according to the American Heart Association. Aim to eat two fish meals per week.