healthy fat: avocados

Long before we knew of "healthy fats," all fats were condemned. In a paper published in the Journal of the History of Medicine and Allied Sciences in 2008, researcher Ann F. La Berge traced the convoluted history of dietary fat and how the United States became swept up in an "ideology of low fat" beginning in the 1960s. For decades, Americans shunned fat, "even though there was no clear evidence that [a low-fat diet] prevented heart disease or promoted weight loss."

Beginning in the early aughts, views on fat began to change, and most health professionals now believe fat is a critical part of the diet. Along with carbohydrates and protein, fat is one of three macronutrients that your body needs to survive and thrive. But just how much fat should you be eating each day? According to the 2015–2020 Dietary Guidelines for Americans, between 20 percent and 35 percent of our daily calories should come from fat. For someone eating 2,000 calories a day, that translates to 44 to 77 grams of fat.

However, not all fats are created equal when it comes to their healthiness. So which fats are good for you and what exactly do they do for the body? This is everything you need to know.

These are the fats you need and the ones you should avoid

foods containing healthy and saturated fats

Fat isn’t a single nutrient. According to WebMD, dietary fat can be divided into four broad categories: saturated, monounsaturated, polyunsaturated, and trans fats. There are many different individual fatty acids within each category; all fats are chains of carbon molecules bonded to hydrogen molecules and it’s the length and shape of these carbon chains and how the hydrogen molecules are attached that gives fats their different properties.

Harvard Medical School identified monounsaturated fats (as found in olive oil and avocados) and polyunsaturated fats (as found in salmon and flaxseeds) as the healthiest fats to consume. Despite their bad reputation, some saturated fats may be healthy if eaten in moderation. Artificial trans fats (in the form of hydrogenated vegetable oils), however, have been linked to a number of health conditions and should be avoided.

The American Heart Association pointed out that there are small amounts of naturally occurring trans fats in some meat and dairy products, but it’s unclear if these natural trans fats have the same negative health impacts as industrially made trans fats.

You’re probably not eating enough of this healthy fat

salmon fillets: healthy fat

According to Healthline, the three omega-3 fatty acids are alpha-linolenic acid (ALA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA). ALA is found predominantly in plants and has little biological importance, while the other two are found mostly in fatty fish and seafood and serve many important functions.

WebMD highlighted omega-3s as beneficial for lowering blood pressure and triglycerides, boosting mood and brain health, and fighting inflammation. According to Medical News Today, shrimp, salmon, oysters, sardines, and seaweed are some of the richest sources of EPA and DHA.

It’s important to eat omega-3s in a proper ratio with omega-6s, another group of polyunsaturated fats. As nutritionist Lisa Richards told Health Digest, this is because omega-6s, while healthy, may cause inflammation that can be balanced out by the anti-inflammatory effects of omega-3s. But most Americans eat way too many omega-6s, especially in the form of vegetable oils used in processed foods, and not nearly enough omega-3s. Richards explained, "It’s recommended to maintain a ratio of 4:1 omega-6 to omega-3 fatty acids, but the standard Western diet ranges between 10:1 and 50:1." The expert recommended eating more omega-3-rich foods and getting your omega-6s from whole-food sources instead of vegetable oils.

Could saturated fat actually be healthy?

steaks on the grill: unsaturated/healthy fat

The 2015–2020 Dietary Guidelines for Americans recommends keeping saturated fat intake to no more than 10 percent of daily calories, but some research suggests that saturated fat isn’t nearly as bad for you as we once thought.

One meta-analysis, for example, published in the American Journal of Clinical Nutrition in 2010, found "no significant evidence for concluding that dietary saturated fat is associated with an increased risk of CHD [coronary heart disease] or CVD [cardiovascular disease]." Another study, led by Dr. Rajiv Chowdhury and published in the Annals of Internal Medicine in 2014, came to the same conclusion. It was also noted that, with the exception of omega-3s, polyunsaturated fats as a whole didn’t provide any particular benefits not found in saturated fat.

Some of the confusion surrounding the healthiness of saturated fats may stem from the fact that there are actually seven distinct dietary saturated fats. According to Healthline, some of these saturated fats, like stearic acid, appear to be healthier than others, such as myristic acid. So while you may not want to go hog wild on the bacon, it’s not fair to label all saturated fats unhealthy.

You should eat these foods for their healthy fats

couple buying olive oil, source of healthy fat

Wondering which foods you should be eating to get the healthy fats your body needs? First, it’s important to realize that even though unsaturated fat is generally found in plants and saturated fat is typically found in meat and animal products, all foods contain a mix of fats. The 2015–2020 Dietary Guidelines for Americans noted that pork fat, for example, is only about 40 percent saturated fat, with another roughly 47 percent coming from monounsaturated fat and the remaining 13 percent coming from polyunsaturated fat. Soybean oil, on the other hand, is about 15 percent saturated fat, 25 percent monounsaturated fat, and 60 percent polyunsaturated fat.

According to Medline Plus, monounsaturated fat is plentiful in nuts, avocados, peanut butter, and a number of cooking oils, including olive, coconut, canola, sesame, and peanut. Polyunsaturated fats can be found in walnuts, sunflower seeds, flax seeds, fatty fish and other seafood, and cooking oils such as corn, soybean, and safflower.

When it comes to saturated fat, Healthline noted that stearic acid, considered the healthiest saturated fat, can be found in animal fat (including meat and dairy products), coconut oil, cocoa butter, and palm kernel oil.

Healthy fats are an important source of energy

avocados: healthy fat

Just like the other macronutrients, your body converts dietary fat into energy that fuels your cells. But unlike the other macronutrients, which provide four calories per gram, fat provides nine calories per gram. Your body uses these calories to power all of the processes necessary for life.

In fact, proponents of the popular ketogenic (keto) diet argue that fat is the preferred source of energy for the body. As Dr. Thomas M. Campbell, medical director of the Highland Weight Management & Lifestyle Center, explained in an interview with the University of Rochester Medical Center, "The ketogenic diet … is a low-carb, moderate protein, high-fat diet. Its purpose is to get the body to burn fats instead of carbohydrates, putting it into a metabolic state known as ketosis." Campbell noted that while this diet strategy can have benefits in the short term, whether it’s healthy and sustainable in the long term is unclear.

Although fats are a great source of energy, Medical News Today advised focusing more on protein and carbs prior to a workout, as fat is absorbed more slowly than carbohydrates or protein and won’t provide the quick energy boost you need.

Healthy fats will help you absorb certain nutrients

healthy fats in dressing

Fat plays an important supporting role when it comes to balanced nutrition. As registered dietitian nutritionist Kristen Carli told Health Digest, "We need to consume fat in order to absorb certain vitamins. Fat-soluble vitamins, including vitamins A, D, E, and K, can only be absorbed by being consumed with a source of fat." According to Healthline, these vitamins perform a number of vital roles in the body, including assisting with vision (vitamin A), boosting the immune system (vitamins A, D, and E), helping with calcium absorption and bone growth (vitamins D and K), and preventing blood clots (vitamin E).

Fat is also needed to absorb carotenoids, plant substances with antioxidant properties. In a 2004 study published in the American Journal of Clinical Nutrition, a research team led by Dr. Melody J. Brown fed participants an all-vegetable salad with either fat-free, reduced-fat, or full-fat dressing and then measured the blood concentration of three carotenoids: beta-carotene, alpha-carotene, and lycopene. The researchers found that no carotenoids were absorbed by participants who ate the fat-free dressing, and those who ate the full-fat dressing absorbed more carotenoids than those who ate the reduced-fat version.

Healthy fats may just protect your heart

healthy fats

Although fat has gotten a bad reputation for its suspected role in causing heart disease, research shows that healthy fats actually decrease your risk for conditions like coronary artery disease and heart attack.

In a meta-analysis published in 2014 in the journal Lipids in Health and Disease, Dr. Lukas Schwingshackl and Dr. Georg Hoffmann examined 32 previously published research studies and concluded that people who consumed the highest amount of monounsaturated fat — specifically oleic acid, most notably found in olive oil — were 12 percent less likely to develop heart disease. Another meta-analysis, conducted in 2010 by a team led by Dr. Dariush Mozaffarian, found that those who consumed the most polyunsaturated fat had a 19 percent lower incidence of heart disease.

These findings could have big implications for many Americans because, according to the Centers for Disease Control and Prevention, heart disease is the leading cause of death in the United States. Coronary artery disease is the most common form of heart disease and affects more than 18 million adults and is responsible for approximately 365,000 deaths each year.

Healthy fats can improve your cholesterol

healthy fats

One reason healthy fats are believed to decrease your risk of heart disease is the positive impact they can have on your cholesterol. According to the Centers for Disease Control and Prevention, 95 million Americans have high total cholesterol (above 200 mg/dL), and 29 million of those have very high cholesterol (above 240 mg/dL). When it comes to high-density lipoprotein (HDL) — aka "good" cholesterol — 18 percent of Americans fell below the recommended level of 40 mg/dL.

A study conducted in 1989 by Dutch researchers and published in the New England Journal of Medicine found that "the serum LDL [low-density lipoprotein/"bad"] cholesterol level decreased by 17.9 percent in those on the monounsaturated fat diet and by 12.9 percent in those on the polyunsaturated fat diet." While the HDL of male participants decreased slightly when eating predominantly monounsaturated or polyunsaturated fats, women’s HDL did not seem to be affected.

Even some saturated fats may be helpful when it comes to improving your cholesterol. A 2005 paper published in the journal Lipids noted that stearic acid, a type of saturated fat, actually lowers bad cholesterol and may increase good cholesterol.

Healthy fats help fight depression

depressed woman

If you’re one of the 17.3 million Americans who’ve experienced at least one episode of major depression, adding more healthy fats to your diet may help prevent future depressive episodes or, at least, ease symptoms.

Known as the SUN Project, a study conducted between 1999 and 2010 sought to determine the relationship between dietary fat and depression. The researchers followed more than 12,000 individuals for 12 years and concluded that while greater trans fat intake increased risk for depression, higher monounsaturated and polyunsaturated fat intake decreased risk. They admitted, however, that the association between monounsaturated fat, polyunsaturated fat, and decreased risk for depression was weak.

When it comes to depression, omega-3s may be the most beneficial polyunsaturated fats. A 2019 meta-analysis led by Dr. Yuhua Liao and published in Translational Psychiatry examined 26 studies and concluded that supplements containing at least 60 percent eicosapentaenoic acid (EPA) showed clinical evidence of improving depression symptoms. Interestingly, docosahexaenoic acid (DHA), another omega-3, showed no benefits. However, if you’re grappling with depression, no amount of fat — regardless of how healthy it is — should take the place of professional therapy or antidepressant medication.

Healthy fats may lower your risk for certain cancers


According to the Centers for Disease Control and Prevention, cancer is the second leading cause of death in the United States, claiming the lives of approximately 600,000 people each year. The National Institutes of Health reported that of the cancer-related deaths in 2020, 9 percent were from colon and rectum cancer and 7 percent are from breast cancer.

While there are many factors that can impact cancer risk, healthy fats have been shown to lower your chances of getting these types of cancer. For instance, a 2007 study published in the American Journal of Epidemiology found that omega-3 fatty acids — eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), specifically — reduced colorectal cancer risk.

Another study, headed by Dr. Carol J. Fabian and published in the journal Breast Cancer Research in 2015, found that women who ate the most omega-3s had the lowest risk for breast cancer. Again, EPA and DHA were the specific fats credited with this protective ability. The researchers also speculated that for those patients with breast cancer, these fats could help reduce the weight gain and muscle loss sometimes associated with chemotherapy.

If you’re trying to conceive, consider upping your intake of healthy fats

pregnant woman

Although it’s a topic often shrouded in shame, infertility is a very common condition. According to the National Institutes of Health, approximately 11 percent of women and 9 percent of men struggle with infertility, which is defined as the inability to conceive after a year of trying. As the Centers for Disease Control and Prevention explained, the female reproductive system relies on a number of hormones, and disruptions in any of these can cause fertility problems.

Eating more healthy fats may improve a woman’s fertility because the body needs fat to create hormones. One 2016 study, for example, found that increased intake of the polyunsaturated fat docosapentaenoic acid was associated with increased progesterone levels and a lower incidence of anovulation (lack of ovulation).

The University of Pittsburgh Medical Center, reporting on research conducted in Spain, highlighted that only 17 percent of women following the Mediterranean diet (rich in monounsaturated and polyunsaturated fats) reported infertility issues, while 26 percent of women eating the typical Western diet (high in saturated and trans fats) experienced infertility.

Eating healthy fats could reduce your risk for type 2 diabetes

person checking blood sugar

According to the Diabetes Research Institute Foundation, the rate at which diabetes is increasing in the United States is cause for alarm. Approximately 34.2 million Americans have the disease. In 2018 alone, an additional 1.5 million cases were diagnosed. It is the seventh leading cause of death in the U.S., directly causing or contributing to more than 270,000 deaths a year.

Certain fats, however, may help prevent type 2 diabetes. In a 2009 study published in the journal Progress in Lipid Research, a team of researchers led by Dr. Ulf Risérus found that the omega-6 fat linoleic acid improved insulin sensitivity. The study’s authors noted that fats can impact glucose metabolism by changing how the membranes of the body’s cells function, and they suggested that replacing saturated and trans fats in the diet with monounsaturated and polyunsaturated fats can lower diabetes risk.

A study published in the journal Current Nutrition Reports in 2018 also found certain fats reduced the risk of type 2 diabetes, although the stars of this study were the omega-3 fats found in fish and seafood and the saturated fat and natural trans fats found in full-fat dairy products.

Healthy eyes require healthy fats

healthy eyes

If you want to safeguard your eyes against disease and vision loss, eating more healthy fats may be the answer. A 2005 study in the journal Progress in Retinal and Eye Research examined the impact of omega-3s on a number of factors that can damage eyes and it was found that these fats may offer protection against eye damage caused by ischemia (inadequate blood supply), light exposure, oxidative stress, inflammation, and aging.

For those suffering from dry eye, omega-3s may also be useful. A 2011 study published by a team of University of Texas Southwestern Medical Center researchers in the journal Cornea found that supplementing with these fats increased tear volume and tear production in participants.

And don’t forget that fat makes it possible for the body to absorb vitamin A. According to the American Academy of Ophthalmology, this fat-soluble vitamin plays many important roles in vision; vitamin A deficiency is the leading cause of preventable blindness in children worldwide. The eye uses vitamin A to create necessary lubrication as well as pigments that allow us to perceive the full spectrum of visible light.

Healthy fats may fight inflammation

healthy fats

Just like fat, some types of inflammation are good for you and others are not. As the Harvard Medical School explained, acute inflammation occurs immediately after an injury and produces warmth, redness, swelling, and pain. This brings white blood cells, which protect the area and begin the healing process. But if the inflammatory response becomes chronic, the body becomes confused and begins attacking healthy tissue. Chronic inflammation is believed to be at the root of many conditions, including cancer, obesity, type 2 diabetes, and heart disease.

Healthy fats, however, have anti-inflammatory properties. One meta-analysis, published in 2006 in the journal Arteriosclerosis, Thrombosis, and Vascular Biology, noted that the monounsaturated omega-9 fat oleic acid (most notably found in olive oil) appears to have anti-inflammatory properties. But the paper’s lead author, Dr. Arpita Basu, cautioned that "further research is needed to define the role of individual dietary factors on the biomarkers of inflammation."

Additionally, a study published in the American Journal of Clinical Nutrition in 2006 noted that omega-3 supplements also seemed to have a clear beneficial impact on some inflammatory conditions (such as rheumatoid arthritis), though much less of an effect on others (such as asthma).