Fat is a type of nutrient. You need some fat in your diet but not too much. Fats give you energy and help your body absorb vitamins. Dietary fat also plays a major role in your cholesterol levels.

But not all fats are the same. You should try to avoid:

• Saturated fats such as butter, solid shortening, and lard
• Trans fats. These are found in vegetable shortenings, some margarines, crackers, cookies, snack foods, and other foods made with or fried in partially hydrogenated oils (PHOs). By 2018, most U.S. companies will not be allowed to add PHOs to food.

Try to replace them with oils such as canola, olive, safflower, sesame, or sunflower. Of course, eating too much fat will put on the pounds. Fat has twice as many calories as proteins or carbohydrates.

Our body needs us to consume some fat in order to work properly. Fat comes from a variety of sources, including dairy, meats, nuts, and oils. It can also be found in many fried, baked, and pre-packaged foods.

Fat is a major source of energy and helps our bodies absorb vitamins. It is also important for proper growth, and for keeping us healthy. A completely fat-free diet would not be healthy, yet it is important that fat be consumed in moderation.

It is important to keep in mind that fat has the most calories compared to any other nutrient. Controlling fat intake is one of the most important steps in losing or maintaining weight and preventing type 2 diabetes. 

How does fat affect my health?

Since our bodies only need a certain amount of fat each day, any extra that we eat is stored in fat tissue and causes us to gain weight. Fat can also be healthy or unhealthy for our heart, depending on which kind we eat.

What are the different types of fat, and which are healthy?

There are four main types of fat:

The goal is to try to choose more of the healthier fats, eat fewer unhealthy fats, and stay within your fat gram goal.

With the winter holidays upon us, you’ll likely be surrounded by family, friends and plenty of good food. Many of these foods, though, can be high in fat. Learn which fats are naughty and which are nice to your health. Then you can make smarter food choices.

We need a certain amount of fat in our diets to stay healthy. Fats provide needed energy in the form of calories. Fats help our bodies absorb important vitamins—called fat-soluble vitamins—including vitamins A, D and E. Fats also make foods more flavorful and help us feel full. Fats are especially important for infants and toddlers, because dietary fat contributes to proper growth and development.

“Fats are really the most concentrated source of energy in the foods we eat, and our bodies need that energy,” says NIH nutritionist Dr. Margaret McDowell. “Fats are truly an essential nutrient.”

Problems arise, though, if we eat too much fat. Dietary fats have more than twice as many calories per gram as either proteins or carbohydrates like sugar and starch. Excess calories, of course, can pack on the pounds and raise your risk for diabetes, cancer and other conditions.

Eating the “wrong” kinds of fats can trigger additional health hazards. “Some fats are better for our bodies than others,” McDowell says. “We should really aim to eat the right types of fats.”

Foods can contain a mixture of different fats. Unsaturated fats are considered “good” fats. They’re sometimes listed as “monounsaturated” and “polyunsaturated” fat on Nutrition Facts labels. These can promote health if eaten in the right amounts. They are generally liquid at room temperature, and are known as oils. You’ll find healthful unsaturated fats in fish, nuts and most vegetable oils, including canola, corn, olive and safflower oils.

The so-called “bad” fats are saturated fats and trans fats . They tend to be solid at room temperature. Solid fats include butter, meat fats, stick margarine, shortening, and coconut and palm oils. They’re often found in chocolates, baked goods, and deep-fried and processed foods.

“When we eat too many solid fats, we put our bodies at risk. These fats tend to raise total blood cholesterol , as well as the part of cholesterol known as low-density lipoprotein (LDL) cholesterol,” says McDowell. “When those cholesterol levels are out of whack and too high, it’s a risk factor for cardiovascular disease.”

“When there’s too much cholesterol in the blood, the excess can get trapped in artery walls and build up,” adds Dr. Catherine Loria, an NIH expert on nutrition and heart health. “The buildup can develop into atherosclerosis, or hardening of the arteries, which can lead to coronary heart disease.”

Experts say that the total fat intake for adults ages 19 and older should be 20% to 35% of the calories eaten each day. For children ages 4 to 18, it should be 25% to 35%.

Experts also say you should get less than 10% of your calories from saturated fatty acids. NIH-funded studies have shown that replacing the solid fats in your diet with healthful unsaturated fats can have a positive impact. “When you look at total fat intake, using unsaturated fats in place of some of the saturated fats actually lowers your total cholesterol levels, and mainly your LDL cholesterol levels, which is a good thing,” says Loria.

Other NIH-funded research found that, when it comes to weight loss, the source of calories—whether from fat, protein or carbohydrate—isn’t as important as the number of calories you consume. But when it comes to risk factors for heart disease, replacing some carbohydrates with protein or unsaturated fats can greatly improve blood cholesterol. In a specialized diet designed to lower blood pressure, using unsaturated fats in place of some carbohydrates boosted blood levels of “good” cholesterol (HDL cholesterol) and caused a more healthful drop in blood pressure.

“It’s about becoming a label reader,” says Joanne Gallivan, a registered dietitian who heads NIH’s National Diabetes Education Program. To eat healthy, she says, “you need to read the Nutrition Facts label to learn the amount of fat and calories in the food, the amounts per serving, and what percent of calories come from fat.” The nutrition label also shows the amounts of unhealthy saturated and trans fats.

Eating healthy fats and less total fat can be especially challenging over the holidays, however. “You want to enjoy the foods and the celebration. You shouldn’t think of the holidays as a time to deprive yourself,” says McDowell.

One way to cut fat at holiday gatherings is to simply reduce your portion sizes. “Choose more lean meats, like poultry without the skin. Eat more fruits, vegetables and whole-grain foods,” says Gallivan.

When preparing recipes, try to use lower-fat ingredients. “Low-fat and fat-free yogurt and milk still contain the important proteins and minerals found in the full-fat versions, but you’re getting less saturated fat and cholesterol,” McDowell says. “In some recipes, you can use applesauce or egg whites, instead of oil. In general, bake, broil or grill instead of frying.”

Learn to read between the lines on Nutrition Facts labels. “If a food is labeled ‘low-fat,’ that doesn’t necessarily mean it’s low in calories,” says Gallivan. Nonfat cookies, crackers and other products may contain added sugar and salt to boost their flavor. Added sugar can add calories, and too much salt can raise blood pressure.

“If you indulge a bit over the holidays, just be sure that the next day you go back to following a healthy meal plan and being active,” says Gallivan. And remember, when it comes to saturated or trans fats in your diet, you’ll help your health if you choose wisely and trim the fat.

Limiting “Bad” Fats

• Trim extra fat and skin on meats and poultry before cooking.
• Instead of frying, try baking, steaming, grilling or broiling.
• Use olive or canola oil instead of butter or margarine.
• Choose margarines with liquid vegetable oil as the first ingredient, or butter substitutes that list water as the first ingredient.
• Look for recipes that use applesauce instead of butter or oil.
• Instead of making a double-crust pie, try a single crust.
• Serve fruits for dessert.
• Use fat-free or low-fat dairy products when possible.
• Avoid cream dips, gravy and whipped cream.
• Broth-based sauces, vinegar, salsa, lemon and herbs add flavor, not fat.

Fat is an essential nutrient for our bodies. It provides energy. It helps our guts absorb certain vitamins from foods. But what types of fat should you be eating? Are there any you should avoid?

Recommendations about dietary fat have shifted over the last two decades. From the 1970s through the 1990s, nutrition researchers emphasized eating a low-fat diet.

This was largely because of concerns about saturated fats , explains Dr. Alice H. Lichtenstein, who studies diet and heart health at Tufts University. Saturated fat that’s in the bloodstream raises the levels of LDL cholesterol—the “bad” cholesterol. This in turn raises the risk of heart disease.

But when people started following low-fat diets, they didn’t only cut saturated fats. In many cases, they replaced healthy unsaturated fats with processed carbohydrates , explains Lichtenstein.

“Initially, when we recommended cutting total fat we did not anticipate people would replace it with fat-free foods, like cookies, crackers, and ice cream, made with refined grains and sugar,’” says Lichtenstein. “It is what we refer to as an unanticipated consequence.”

As scientists have learned, those replacement calories matter. Studies have shown that replacing saturated fat with unsaturated fat reduces the risk of heart disease. However, replacing saturated fat with simple carbohydrates, such as added sugar and white bread, does not.

“There’s still this misconception that eating fat—any kind of fat—is bad. That it will lead to heart attacks, or weight gain. That’s not true. People really should be encouraged to eat healthy fats,” says Dr. Frank Sacks, a nutrition expert at Harvard University.

Healthy Fats

Research has shown that unsaturated fats are good for you. These fats come mostly from plant sources. Cooking oils that are liquid at room temperature, such as canola, peanut, safflower, soybean, and olive oil, contain mostly unsaturated fat. Nuts, seeds, and avocados are also good sources. Fatty fish—such as salmon, sardines, and herring—are rich in unsaturated fats, too.

Large studies have found that replacing saturated fats in your diet with unsaturated fats can reduce your risk of heart disease by about the same amount as cholesterol-lowering drugs.

People should actively make unsaturated fats a part of their diet, Sacks says. You don’t need to avoid healthy fats to lose weight, he adds.

In an NIH-funded study Sacks led, called the POUNDS LOST trial, people who ate higher-fat or lower-fat diets had similar rates of weight loss. They were also both successful at keeping the weight off.

“Low-fat diets have the same effect on body weight gain or weight loss as higher-fat diets, or higher-protein diets,” he explains. “For weight loss, it’s about getting a handle on whatever foods in your diet are giving you excess calories.”

Replacing ‘Bad’ Fats

So are there fats you should avoid? Only a few years ago, doctors still had to advise people to avoid so-called trans fats in their diets. These largely manufactured fats could be found in things like margarine and many processed foods. They have been shown to raise the risk of heart disease.

Since 2015, the U.S. Food and Drug Administration has taken steps to remove artificial trans fats from the food supply. Most trans fats now in food come from the small amounts found naturally in animal products, like meat and butter.

Experts already recommend that people limit their intake of animal fats. “So that takes care of those trans fats as well,” Lichtenstein says.

As for saturated fat, it’s complicated. Not all of the saturated fat in the bloodstream comes from the saturated fat that we eat, explains Dr. Ronald Krauss, who studies cholesterol at the UCSF Benioff Children’s Hospital Oakland. Instead, it’s produced when the body breaks down simple carbohydrates and sugars. That’s one reason why replacing saturated fat in the diet with simple carbohydrates doesn’t reduce the risk of heart disease.

Nutrition experts still recommend that people minimize the amount of saturated fat in the diet. But researchers are now looking at whether the type of food that saturated fat is found in matters. For example, the influence of plant-based saturated fats, such as those in coconut and palm oil, is still unclear and being researched further.

Recent studies suggest that some full-fat dairy products, such as yogurt, may actually have benefits for the heart, Krauss says.

Krauss and his colleagues recently ran a small study looking at the effects of replacing some of the sugar allowed in the DASH diet with saturated dairy fats. The DASH diet was developed by NIH to help lower blood pressure.

Participants who ate saturated dairy fat instead of sugar had less of a fat called triglycerides in their bloodstream. The higher-fat diet was also as effective at lowering blood pressure as the standard DASH diet.

More research is needed to understand which foods that contain saturated fats may influence the body in a good way.

Individual Needs

Researchers know that there are big differences in how people’s bodies react to different types and amounts of fat. But they still don’t know why. Studies have found that genes aren’t likely responsible, Sacks explains.

Lichtenstein and Krauss are both studying how the microbes that live in the gut interact with dietary fats. The makeup of the microbiome—all the microorganisms that normally live in the body, mainly in the gut—can differ widely between people.

It may turn out that different types of gut bacteria produce different compounds from fats. These compounds could then affect the body in different ways, Lichtenstein explains. Or different types of fats could promote the growth of different bacteria in the gut, which may then have varying effects on health.

“We just don’t know yet, but there is tremendous interest in trying to understand the role of the gut microbiome in human health,” she says.

If there’s one thing that the research has shown, it’s that the science of diets is very complex. Experts have moved away from focusing on single nutrients—such as fat—by themselves. Instead, Sacks says, researchers now talk about healthy dietary patterns: ways of eating that take all aspects of the diet into account.

Choosing Your Fats

• Eat plant-based foods. Plants can contain healthy fats, as well as important vitamins and minerals.
• Include plant oils in your diet. Healthy choices include canola, peanut, olive, safflower, soybean, sunflower, corn, and nut oils.
• Replace foods containing saturated fats (like butter or lard) with healthier unsaturated fat options.
• Limit fatty red meat. Instead, eat more fish, poultry, or lean meats.
• Reduce sugars and replace processed grains, such as white bread and white rice, with whole grains and brown rice. The body can use simple carbohydrates to make saturated fats.

Oils are fats that are liquid at room temperature, like vegetable oils used in cooking. Oils come from many different plants and from fish. Oils are not a food group, but they provide important nutrients such as unsaturated fats and vitamin E. A number of foods are natural sources of oils, like nuts, olives, some fish, and avocados. Most oils are high in monounsaturated or polyunsaturated fats, and low in saturated fats. Foods that are mainly made of oil include mayonnaise, certain salad dressings, and soft (tub or squeeze) margarine. The fat in some tropical plants, including coconut oil, palm oil, and palm kernel oil, are not included in the oils category because they are higher in saturated fats than other oils.

Solid fats are fats that are solid at room temperature, like butter, lard and shortening. Solid fats come from many animal foods and can be made from vegetable oils through a process called hydrogenation.

Choosing oils in place of solid fats can help support healthy dietary patterns by helping to reduce intakes of saturated fats. For those who are 2 years of age and older, the Dietary Guidelines recommend limiting intake of saturated fat to less than 10 percent of calories per day by replacing them with unsaturated fats, like those found in oils and foods that contain mainly oils.

Omega-3 fats are an especially “heart healthy” fat and can help with lowering high triglyceride values in your blood. Omega-3 fats can be found in:

• Fish: salmon, mackerel, herring, sardines, albacore tuna, and rainbow trout
• Tofu and other soybean products
• Walnuts
• Flaxseed and flaxseed oil
• Canola oil

Monounsaturated and polyunsaturated fat are considered “heart healthy” and can help with improving cholesterol. Some sources of these fats include:

• Avocado
• Nuts and seeds: almonds, cashews, pecans, peanuts, pine nuts, pumpkin, sunflower, or sesame seeds
• Olive oil and olives
• Oils: vegetable oils (such as sunflower, safflower, corn, soybean, and cottonseed)
• Peanut butter

Saturated fats are mainly found in foods that come from animals (such as meat and dairy), but they can also be found in most fried foods and some pre-packaged foods. Saturated fats are unhealthy because they increase LDL (“bad” cholesterol) levels in your body and increase your risk for heart disease. Many saturated fats are “solid” fats that you can see, such as the fat in meat. Other sources of saturated fats include:

• High-fat cheeses
• High-fat cuts of meat
• Whole-fat milk and cream
• Butter
• Ice cream and ice cream products
• Palm and coconut oils

Trans fat is simply liquid oils turned into solid fats during food processing. There is also a small amount of trans fat that occurs naturally in some meat and dairy products, but those found in processed foods tend to be the most harmful to your health.

Trans fats serve up a double whammy to your cholesterol, by increasing LDL (“bad” cholesterol) and decreasing HDL (“healthy” cholesterol).

In order to avoid trans fat, look on nutrition labels for ingredients such as “partially hydrogenated” oils or shortening. In addition, look for trans fat in the nutritional information in products, such as commercially baked desserts, crackers, and fried foods.

Limit the amount of fat you eat, but don’t try to cut it out completely. Focus on reducing foods high in saturated fat, and trans fat. Always remember to stay within your fat gram goal.

Here are a few more tips for choosing the best types of fat:

• Choose leaner cuts of meat that do not have muchvisible fat. Leaner cuts include round cuts and sirloin cuts. Trim visible fat off meats before eating.
• Sauté with olive oil or canola oil instead of butter.
• Use olive oil in salad dressings and marinades.
• Use canola oil when baking.
• When re-heating soups or stews, skim the solid fats from the top before heating.
• Sprinkle slivered nuts or sunflower seeds on salads instead of bacon bits.
• Snack on a small handful of nuts rather than potato chips or processed crackers.
• Try peanut butter or other nut-butter spreads (which do not contain trans fat) on celery, bananas, or low-fat crackers.
• Add slices of avocado rather than cheese to your sandwich.
• Once or twice a week prepare fish, such as salmon or mackerel, instead of meat.