Not so long ago, all fat was considered the mortal enemy in the fight for good health, especially for cardiovascular health. The good news is that science has since proven that all fats are not created equal. In fact, some types of fat actually promote better health — even heart health.
With cardiovascular disease the leading global cause of death, knowing the difference between good fats and bad fats is key.
What Are Fats?
Fats, technically called fatty acids, are chemical chains of carbon atoms differing in length, shape and the number of hydrogen atoms. The differences in their chemical composition affect whether they are healthful or harmful.
All fats and oils have varying amounts of saturated, unsaturated and polyunsaturated fatty acids. When fats are described as being saturated, for example, it means that most of the fatty acids in the food are saturated.
In general, most unsaturated fats are liquid at room temperature, while most saturated fats are solid — with the exception of tropical oils, such as palm oil and coconut oil, which are liquid.
There are many different types of fat. Your body makes fat (adipose tissue) from extra calories, and fat comes in both plant and animal foods that you eat.
Fat is essential to your health. Everyone needs fat in their diets, but choosing the right ones and in the right amounts is key.
“Fats provide a major source of fuel, aid in the absorption of fat-soluble vitamins, help meet essential fatty acid requirements and are vital for brain development in infants and children,” says registered dietitian nutritionist and Columbia University research scientist Wahida Karmally. “Healthy fats, like unsaturated olive oil, can be cardioprotective because of their anti-inflammatory properties. Unhealthy fats, such as saturated and trans fats, have been shown to increase cholesterol, inflammation, insulin resistance and risk of heart disease and Type 2 diabetes.”
Keep in mind that all fats — even good fats — are high in calories and can contribute to weight gain. Each gram of fat provides nine calories.
[READ: Surprisingly High-Fat Foods.]
Good Fats vs. Bad Fats
Good fats are unsaturated fats, including monounsaturated and polyunsaturated fatty acids. These fats are heart healthy and the best choices for fats. Good fats are primarily found in liquid oils, nuts, seeds and fish.
Monounsaturated fatty acids
These are found in many types of foods and oils. Eating foods rich in monounsaturated fatty acids instead of saturated fats has been shown to improve cholesterol levels, which can decrease your risk of heart disease and Type 2 diabetes.
Sources: nuts, vegetable oils, nut butters, avocado, olives.
Polyunsaturated fatty acids
Found mostly in plant-based foods and oils, these fats also improve blood cholesterol levels. Polyunsaturated fatty acids cannot be made in the body. Therefore, they are considered essential. Omega-3 fatty acids are a type of polyunsaturated fat that appears to be especially beneficial for heart health. These fats help reduce chronic inflammation and may decrease the risk for heart disease.
Sources: Cold water fish such as salmon, trout, sardines and herring, walnuts, flaxseed, chia seeds, canola oil, tofu, soybean oil, safflower oil, sunflower oil and flaxseed oil.
Saturated fatty acids
Saturated fats raise total cholesterol and low-density lipoprotein (LDL or bad) cholesterol levels, which may increase your risk of cardiovascular disease.
They are found primarily in animal sources but also in tropical oils. In fact, coconut oil is the most saturated fat of them all. While some controversy exists over the limit on saturated fat, it has been shown that replacing saturated fat with polyunsaturated fats, particularly omega-3 fatty acids, can reduce risk of heart disease. Conversely, studies have shown that swapping refined carbs for saturated fats is actually worse for overall health.
Sources: beef, pork, lamb, dark meat poultry, poultry skin, bacon, high fat dairy (milk, butter, cheese, sour cream, yogurt, ice cream), coconut oil, palm oil, cocoa butter, lard, baked goods.
Trans fats
Man-made trans fats are unquestionably bad fats. Most trans fats are man-made from oils in a process called hydrogenation, which turns healthy oils into solids. These fats are considered the worst type of dietary fat and have been banned in the United States.
“There is strong evidence that excessive trans fats in the diet are a significant risk factor for cardiovascular disease, as well as a risk factor for cancer and diabetes. A 2% absolute increase in intake from trans fat has been associated with a 23% increase in cardiovascular risk,” says Karmally.
Trans fats can create inflammation, boost total blood cholesterol, low-density lipoprotein (LDL or bad) cholesterol and triglyceride levels while also lowering high-density lipoprotein (HDL or good) cholesterol, all of which can increase your risk of cardiovascular disease. They can also promote insulin resistance, which increases risk for Type 2 diabetes.
Sources: Even though they are banned, you may find them in margarine, shortening, snack foods and baked goods.
“We cannot totally avoid trans fats due to their natural presence in dairy and meat products,” says Karmally. Read food labels carefully. Even products that list zero trans fats can have as much as .5 grams per serving. To avoid trans fats, choose foods make with non-hydrogenated oils.
[Read: Anti-Cancer Foods.]
How Much Fat Is OK?
The 2020-2025 Dietary Guidelines for Americans from the U.S. Department of Agriculture and the U.S Department of Health and Human Services, recommend the following targets for healthy adults:
Total fat: 20% to 35% of daily calories.
Saturated fat: 10% or less of daily calories starting at 2 years of age.
For example, on a 2,000-calorie per day diet, 400 to 700 calories should come from fat, or 45 to 75 grams of fat per day. Of that amount, only 4.5 to 7 grams per day, or less than 10%, should come from saturated fat.
The American Heart Association presidential advisory on dietary fats and cardiovascular disease recommends lowering the intake of dietary saturated fat and replacing it with polyunsaturated fats. According to the AHA, substituting polyunsaturated fats for saturated fats can reduce cardiovascular disease risk by about 30%, similar to the reduction achieved by statin treatment.
[READ: Using Food As Medicine]
Eating Good Fats as Part of a Heart-Healthy Diet
Dietary patterns, or what you typically eat, are central to good health and disease prevention.
“It is not just about choosing the right fats but it must be within the context of a healthy dietary pattern like the Mediterranean diet, ” recommends Karmally.
Healthy dietary patterns emphasize fruits, vegetables, nuts, whole grains, lean protein, low fat dairy and seafood with limited amounts of red and processed meats, refined carbs, sugar-sweetened foods and beverages.
Healthy dietary patterns also fight inflammation.
“Inflammation in the body is a response to any substance such as unhealthy foods eaten on a regular basis or poisons that enter our bodies” explains Karmally. “Inflammation can show up as health problems such as heart disease, cancer, diabetes or inflammatory bowel disease.”
Tips for Choosing Healthy Fats
— Whenever possible, choose vegetable oils instead of solid fats. For example, use extra virgin olive oil instead of butter.
— Eat more fish. The 2025 DGA recommends 8 ounces of seafood per week on a 2,000 calorie diet.
— Limit fried foods to once or twice a week because they are higher in calories and typically high in trans fats.
— Choose more plant protein, lean meat and skinless poultry instead of higher fat and processed meats.
— Read labels and avoid products with “partially hydrogenated” oils.
— Replace saturated fats with healthy unsaturated fats or whole-grain, high-fiber carbohydrates.
— Eat more avocados. Try them on sandwiches, add to salads or load them with whole-grain medleys.
— Snack on olives or nuts.
Bottom Line
Healthy fats are an important part of your overall diet, providing great taste and flavor to food while satisfying nutritional needs and providing health benefits.
Enjoy unsaturated fats, limit saturated fats and avoid trans fats as part of a healthy diet that includes a wide variety of healthy foods along with regular physical activity.
More from U.S. News
Healthy and Delicious Ways to Eat Avocado
What Foods Are Good for Your Liver?
The Truth About Fats, Cholesterol and Heart Health: Good Fats vs. Bad Fats originally appeared on usnews.com
Update 02/02/24: This story was previously published at an earlier date and has been updated with new information.
