The first thing to know about “good” and “bad” fats is that those terms are tricky.
“I don’t like to say ‘good fats’ or ‘bad fats’ because people often perceive themselves as ‘good’ if they eat ‘good fats’ and ‘bad’ if they eat ‘bad fats.’ This can play into a diet mentality of guilt and shame,” says Jessica Bennett a clinical dietitian at Vanderbilt University Medical Center. “Some fats are healthy and others are less healthy.”
Less-healthy fats raise can your level of less-healthy cholesterol (LDL). This can cause issues in your arteries and can lead to heart attacks and strokes.
Healthy fats are an important part of your daily diet. Your body needs them for energy, brain health, cell growth, organ protection, hormone production, and to keep you warm. Fats also help you absorb some nutrients and keep you fuller longer.
Healthy: Unsaturated Fats
There are two kinds of unsaturated fats: monounsaturated and polyunsaturated. Unsaturated fats are liquid at room temperature.
Unsaturated fats include omega-3 fatty acids and omega-6 fatty acids. Both are “essential” fatty acids, meaning that your body can’t make them so you need to get them from your diet.
How they affect heart health: Unsaturated fats help improve healthy cholesterol levels when used instead of saturated fats. Omega-3 fatty acids have been studied for a wide range of health benefits. When it comes to the heart, they may help lower triglycerides (a type of blood fat), lower high blood pressure, and help prevent congestive heart failure in older adults. Many studies show a lower risk of heart disease in people who regularly eat omega-3-rich fish as part of a healthy diet.
How much: All fats have 9 calories per gram. Between 8% and 10% of your daily calories should come from unsaturated fats. Use them sparingly: Even though olive oil is better for you than butter, it still has a lot of calories. Use a spray bottle instead of a spout. The American Heart Association recommends two servings of fish rich in omega-3s (such as salmon, mackerel, herring, sardines, and albacore tuna) per week. A serving is 3.5 ounces of cooked fish. There are also plant-based sources of omega-3 fatty acids, including flaxseed, chia seed, and walnuts. Some products are fortified with omega-3s, too.
- Canola oil
- Corn oil
- Fatty fish such as salmon, mackerel, herring, tuna, and sardines
- Flaxseed oil
- Olive oil
- Peanut oil
- Soybean oil
- Sunflower oil
Less Healthy: Saturated Fats
Most foods have a mix of different kinds of fats. The goal is to have more unsaturated fat than saturated. Chicken and peanuts are healthy foods that have low amounts of saturated fat. Coconut oil, which sounds healthy but has no proven health benefits, is 82% saturated fat.
How they affect your heart health: Saturated fats raise the level of unhealthy cholesterol in your blood. This puts you at a higher risk of heart disease and stroke.
How much: The American Heart Association wants 6% or less of your calories to come from saturated fat. For example, if you aim for 2,200 calories a day, 132 of them should come from saturated fat. Replace saturated fats with unsaturated fats like fruits, vegetables, whole grains, and low-fat dairy products, not refined carbs like pretzels and ready-to-eat cereals.
- Chicken with the skin on
- Coconut oil
- Dairy desserts
- Fast food
- Fatty beef
- Reduced-fat milk
- Whole milk
Less Healthy: Trans Fats
There are two types of trans fats. Naturally occurring trans fats come from the guts of some animals and products made from them, like meat and dairy. Artificial trans fats are made when companies add hydrogen to vegetables oils to make them solid. “These are the fats you want to say away from,” Bennett says. “They’re very unhealthy.”
How they affect heart health: When you eat foods that contain trans fats, your healthy cholesterol goes down and your unhealthy cholesterol goes up. This puts you at risk for heart disease, stroke, and type 2 diabetes. Trans fats also cause inflammation.
How much: The short answer is: none to as little as possible. It helps that the FDA has banned trans fat from most processed foods in the U.S.
Sources: Trans fats are often listed as partially hydrogenated oils on ingredient lists. Even though they’re banned, makers can still include less than 0.5 grams per serving in “0 trans fat” foods.
- Doughnuts and other fried desserts
- Baked goods like pies, cakes, and cookies
- Frozen pizza
Fats, Fads, and Balance
Diets like keto and paleo have gotten a lot of attention lately. But if a food plan calls for eating lots of fat, and you get it from saturated fat, that raises your levels of unhealthy cholesterol. In the long run, that could be bad for your heart.
“When you hear about the latest ‘diet of the day,’ or a new or odd-sounding theory of food, consider the source,” says Alice H. Lichtenstein, DSc, Gershoff professor of nutrition science and policy at Tufts University. “Decades of sound science shows that replacing saturated fat with unsaturated fat, particularly polyunsaturated fat, lowers LDL cholesterol concentrations and cardiovascular disease risk.”
Unlimited fat can have drawbacks. For instance, even though avocado and olive oil provide healthy fat, you want to keep an eye on the serving size so they stay within your calorie budget.
“It all goes back to balance,” Bennett says. “Don’t focus on one trend or nutrient and forget about the big health picture.”
If you eat a high-fat food, balance it out with fruits and vegetables. Not only do they give you nutrients, they add fiber that can bind to some of the calories and fat and pull them out of your body.