Polyunsaturated fats. When you pour liquid cooking oil into a pan, there's a good chance you're using polyunsaturated fat. Corn oil, sunflower oil, and safflower oil are common examples. Polyunsaturated fats are essential fats. That means they're required for normal body functions but your body can't make them. So you must get them from food. Polyunsaturated fats are used to build cell membranes and the covering of nerves. They are needed for blood clotting, muscle movement, and inflammation.
Polyunsaturated fats can primarily be found in plant-based foods and oils. Similar to monounsaturated fats, polyunsaturated fats can decrease the risk of heart disease by lowering levels of blood cholesterol (9). A certain type of polyunsaturated fat, omega-3 fatty acids have been found to be particularly beneficial for heart health. They not only lower the risk of coronary artery disease but can also lower blood pressure and protect against irregular heartbeats (9). Omega-3 fatty acids can be easily consumed by eating fatty fish such as salmon, sardines and trout.
But wait, bile isn’t the only thing added in here, our pancreas also adds pancreatic digestive juices called lipase to the duodenum which helps break down triglycerides into two fatty acids and a monoglyceride. After this step, though, the fat droplets don’t just disappear. Instead the fatty acids and monoglycerides are absorbed in the microvilli (remember these from Digestion, part I?) and reassembled into triglycerides.
Trans fats are unsaturated fats that have been processed and as a result, behave like saturated fats. Eating trans fats increases the levels of ‘bad’ cholesterol and decreases the levels of ‘good’ cholesterol in the body which is a major risk factor for heart disease. It is important to lower the amounts of trans fats you eat to help you stay healthy.
Walnuts are one of the best sources of omega-3 fatty acids, specifically alpha linoleic acid, an omega-3 found in plants. A recent study linked a handful per day to lower total cholesterol and LDL cholesterol as well as improved blood vessel function. Research has also shown that eating nuts appears to reduce the risk of blood clots that can cause heart attacks as well as improve the health of the lining of our arteries.
Although fat is an essential part of the diet, keep in mind that most high-fat foods are also considered calorie-dense foods. When increasing your intake of healthy fats, it’s important to account for this by making modifications to your diet, such as decreasing your intake of refined carbs or sweets. Without making a few simple swaps to your diet, adding high-fat, high-calorie foods can lead to weight gain.

Omega 3 fatty acids and omega 6 fatty acids are both a type of polyunsaturated fat. For a healthy body, omega 3 and omega 6 fatty acids need to be eaten in about a 1:1 ratio. However, the standard American diet contains about 15 to 16 times as many omega 6s as omega 3s, so the ratio is way out of whack. Omega 6 fatty acids eaten in a high concentration like that become pro-inflammatory and promote heart disease.
Canola oil, derived from the seeds of a plant in the broccoli family, has a near-perfect 2.5:1 ratio of omega-6 to omega-3 fats. According to a study review published in Experimental Biology and Medicine, people who achieve a dietary ratio similar to this have been able to battle cancer, arthritis, and asthma more effectively. The neutral oil is also rich in alpha-linolenic acid (ALA), an essential omega-3 fatty acid that may play a role in weight maintenance, according to a recent study.
You'll primarily find saturated fat in animal-derived foods, particularly fatty red meat and processed meat. And while recent research has called into question exactly how big of a negative impact saturated fat has on your health, Harvard recommends replacing sources of saturated fat with unsaturated fat. Grilling up salmon instead of a burger, for example, fits the bill.

Food manufacturers flooded the market with processed foods containing hydrogenated fats and processed sugar. The replacement of saturated fats in the diet with trans fats and sugar resulted in epidemic rates of obesity and its related health complications (2). Rates of diabetes, heart disease and cancer have risen since Americans adopted the low-fat, high-carbohydrate diet.
Cheese often gets a bad-rap for being a high-fat food—especially hard, full-fat cheeses like Parmesan. While it is true that cheeses have more saturated fats than plant based foods, they (especially Parmesan, which contains 8 grams fat and 5 grams saturated fat per ounce), provide loads of other nutrients as well. In fact, Parm tops the cheese charts in terms of its bone-building calcium content, providing nearly a third of your daily calcium needs. Ounce for ounce, it has more protein than any other food—and yes, we are including meat and eggs on that list!
Olives are rich in monounsaturated fat. Add them to salads or snacks, and cook with olive oil whenever possible as part of a heart-healthy diet. “Olive oil is made up of triglycerides that contain a very large percentage of monounsaturated fatty acids,” says Janet Bond Brill, PhD, a registered dietitian and author of Cholesterol Down: 10 Simple Steps to Lower Your Cholesterol in 4 Weeks Without Prescription Drugs and Prevent a Second Heart Attack: 8 Foods, 8 Weeks to Reverse Heart Disease. “Up to 80 percent of olive oil is monounsaturated, primarily the omega-9 fatty acid known as oleic acid. The high monounsaturated fatty acid content of olive oil is extremely cardioprotective — it cuts your ‘bad’ cholesterol level, helps prevent atherosclerosis, and can bump up your level of HDL, the ‘good’ cholesterol.” Try this simple olive-based side dish of chard with green olives, currants, and goat cheese.
All fats and oils contain fatty acids. You may be most familiar with Omega 3 fatty acids, found in fish oil. When you eat healthy fats and oils, the digestion process enables the fatty acids to be absorbed into the blood. Fatty acids are a component of fats and oils that become the building blocks of your body, helping to create cells membranes and nerve sheathing among other body functions.
The dietary reference intake (DRI) for fat in adults is 20% to 35% of total calories from fat. That is about 44 grams to 77 grams of fat per day if you eat 2,000 calories a day. It is recommended to eat more of some types of fats because they provide health benefits. It is recommended to eat less of other types of fat due to the negative impact on health.
Healthy fats have numerous benefits for your body when included as part of a healthy balanced diet. A diet which includes moderate to high amounts of monounsaturated fats can be useful in weight loss, as long as you don’t eat more calories than you are burning. A large study which combined the results of twenty four other studies found that participants who followed a high-monounsaturated fat diet had more effective weight loss than those who followed high-carbohydrate diets (10).
Yes, you need fat in your diet! All three macronutrients – fats, carbohydrates, and protein – are incredibly important for the human body’s functioning. Fats are important for cellular and hormonal health, and unlike carbohydrates and protein, fats also provide our bodies with a layer of protection, literally insulating our organs and also helping keep a normal body core temperature.
Not only does dark chocolate taste great, but it’s also considered a superfood as well. It’s high in fat and rich in antioxidants, which help protect our bodies from disease-causing free radicals. The flavanols found in dark chocolate also improve heart health, thanks to their ability to lower blood pressure and get more blood flowing to the heart and the brain. (31) And if you’ve ever found that nibbling on a piece of chocolate helps you focus, you’re not alone. It’s a brain food that actually helps improve cognitive performance. (32)

While all unsaturated fats are good for you, you'll get more benefits from omega-3 fatty acids. These unsaturated fatty acids can't be produced by your body, so you need to get them from your diet. And they're crucial to your well-being, since they promote good cardiovascular health, play a role in brain function and offer anti-inflammatory benefits. They're also great for your cholesterol, since they increase "good" (HDL) cholesterol levels.
The benefits of avocados are so numerous that they’re one of the healthiest fruits you can consume, not to mention one of the top healthy fats for keto. Avocado nutrition is rich in monounsaturated fats, which raises levels of good cholesterol while lowering the bad — talk about a double-whammy. Avocados are also packed with the benefits of vitamin E, which help fight free radical damage, boost immunity and act as an anti-aging nutrient for your skin. (7)
You may wonder isn't fat bad for you, but your body needs some fat from food. It's a major source of energy. It helps you absorb some vitamins and minerals. Fat is needed to build cell membranes, the vital exterior of each cell, and the sheaths surrounding nerves. It is essential for blood clotting, muscle movement, and inflammation. For long-term health, some fats are better than others. Good fats include monounsaturated and polyunsaturated fats. Bad ones include industrial-made trans fats. Saturated fats fall somewhere in the middle.
What these studies highlight is that when cutting down on saturated fats in your diet, it’s important to replace them with the right foods. For example, swapping animal fats for vegetable oils—such as replacing butter with olive oil—can help lower your cholesterol and reduce your risk for disease. However, swapping animal fats for refined carbohydrates-such as replacing your breakfast bacon with a bagel or pastry-won’t have the same benefits. That’s because eating refined carbohydrates or sugary foods can have a similar negative effect on your cholesterol levels, your risk for heart disease, and your weight.
For years we’ve been told that eating fat will add inches to your waistline, raise cholesterol, and cause a myriad of health problems. But now we know that not all fat is the same. While bad fats can wreck your diet and increase your risk of certain diseases, good fats can protect your brain and heart. In fact, healthy fats—such as omega-3s—are vital to your physical and emotional health. By understanding the difference between good and bad fats and how to include more healthy fat in your diet, you can improve your mood, boost your energy and well-being, and even lose weight.
The worst type of dietary fat is the kind known as trans fat. It is a byproduct of a process called hydrogenation that is used to turn healthy oils into solids and to prevent them from becoming rancid. Trans fats have no known health benefits and that there is no safe level of consumption. Therefore, they have been officially banned in the United States.
Hi, and Thank you for a very interesting website. I read the newsletters with curiousity and I learn new things. I am a Norwegian woman who started with LCHF diet/ keto three months ago. My motivation was serious healthchallenges with IBS, which became increasingly difficult after an gut infection last summer. My gut is much better! Not “perfect”, but the difference from three months ago is huge. My energy level is also coming back to normal, and even better! I have a question about canola oil. I am confused. I thought it was healthy, and that the balance between omega 3 and 6 was good. Canola oil is a preferred oil, together with olive oil, coconut oil and butter, on dietdoctor.com and other lowcarb-websites and books. So I wonder, why is it in your opinion on the “not to eat” list? Is it something that happens with it during the process of production? Or? Kind Regards, Mona Sommer
One cup of black olives has 15 grams of fat, but again, it is mainly monounsaturated. Plus, no matter what variety of olive you enjoy, they all contain many other beneficial nutrients as well, such as hydroxytyrosol, a phytonutrient that has long been linked to cancer prevention. New research is showing that this phytonutrient may play a role in reducing bone loss as well. And if you have allergies or other inflammatory conditions, olives might be just the snack for you as research suggests that olive extracts function as anti-histamines on the cellular level. Even with all these benefits, it is important to be mindful of your serving size as olives can be high in sodium. Stick to 5 large or 10 small olives as the perfect portion.
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