Which Fat Is Bad? What to Choose

Not all fat is bad for you, but some types clearly are. The fats you need to limit are trans fats and excessive saturated fats. The fats you should eat more of are unsaturated fats, especially polyunsaturated and monounsaturated fats found in plants, nuts, seeds, and fish. Understanding which fat is bad comes down to knowing how each type affects your body, and the evidence on this is strong and consistent.

What Is the Difference Between Good Fats and Bad Fats?

The main difference is how each type of fat affects your cholesterol levels and heart health. Bad fats raise your LDL cholesterol, which is the type that builds up in your arteries. Good fats help lower LDL or raise HDL, which is the protective type of cholesterol.

Trans fats are the worst. They raise LDL and lower HDL at the same time. This is a double hit to your heart health. The American Heart Association has stated that trans fats have no known health benefit and no safe level of consumption.

Saturated fats fall in the middle. They raise LDL cholesterol, which is bad. But some research suggests they may not be as harmful as once thought when eaten in moderation. The key issue is what you replace them with. Replacing saturated fat with refined carbs does not help. Replacing it with unsaturated fat does.

Unsaturated fats are the good ones. They come in two forms: monounsaturated and polyunsaturated. Both help improve cholesterol levels. Polyunsaturated fats include omega-3 fatty acids, which have strong evidence for reducing inflammation and supporting heart health.

Which Fat Is Bad for Your Heart?

Trans fat is the single most harmful type of fat for your heart. It is created when liquid oils are turned into solid fats through a process called hydrogenation. Food manufacturers used it for decades because it was cheap and gave foods a longer shelf life.

The evidence against trans fat is overwhelming. Research published in the New England Journal of Medicine found that each 2 percent increase in calories from trans fat raised the risk of heart disease by 23 percent. That is a large effect for a small amount of food.

Saturated fat also raises heart disease risk, but the effect is smaller. A major analysis in the Annals of Internal Medicine found that replacing saturated fat with polyunsaturated fat lowered heart disease risk by about 17 percent. Replacing it with carbohydrates showed no benefit.

The takeaway is clear. Trans fat is the fat to avoid completely. Saturated fat is fine in small amounts, especially if you replace it with unsaturated fats rather than sugar or refined grains.

What Foods Contain the Worst Fats?

Trans fats are found in foods made with partially hydrogenated oils. The FDA banned artificial trans fats in processed foods in 2018, but small amounts can still be present. Foods that may still contain them include microwave popcorn, frozen pizzas, coffee creamers, and refrigerated dough products like biscuits and cinnamon rolls.

Fast food is another source. Fried foods like french fries, chicken nuggets, and doughnuts are often cooked in oils that contain trans fats. The oil is reused multiple times, which can increase trans fat content.

Saturated fat is found in animal products and tropical oils. The main sources are red meat, butter, cheese, whole milk, cream, and palm oil. Coconut oil is also high in saturated fat, though it has become popular in recent years. The American Heart Association advises limiting saturated fat to 5 to 6 percent of your daily calories.

Here is a quick comparison of common fat sources:

What Are the Best Fats to Cook With?

For high-heat cooking like frying or searing, choose oils with a high smoke point. Avocado oil works well because it is mostly monounsaturated fat and can handle temperatures up to 520°F. Grapeseed oil and light olive oil are also good options.

For medium-heat cooking like sautéing, use olive oil or canola oil. Extra virgin olive oil is best for low-heat cooking or dressings because it has a lower smoke point. It also contains antioxidants called polyphenols that support heart health.

For no-heat uses like salad dressings and dips, extra virgin olive oil, walnut oil, and flaxseed oil are excellent choices. These oils are rich in polyunsaturated fats and omega-3s. Do not heat flaxseed oil because it breaks down quickly.

Butter and coconut oil are fine for occasional use, but they should not be your everyday cooking fats. They are high in saturated fat and will raise your LDL cholesterol if used regularly.

How Much Fat Should You Eat Each Day?

The Dietary Guidelines for Americans recommend that 20 to 35 percent of your daily calories come from fat. For someone eating 2000 calories a day, that is 44 to 78 grams of total fat. Within that, saturated fat should be no more than 10 percent of calories, or about 22 grams per day.

The American Heart Association recommends an even lower limit for saturated fat: 5 to 6 percent of calories. That is about 13 grams per day for a 2000-calorie diet. To put that in perspective, one tablespoon of butter has 7 grams of saturated fat. Two tablespoons would nearly max out your limit.

Trans fat should be as close to zero as possible. The World Health Organization has called for the global elimination of industrially produced trans fat by 2023. Many countries have already banned it. In the US, the FDA ban has greatly reduced trans fat in the food supply, but you still need to check labels.

Here are some practical tips for choosing fats:

• Use olive oil or avocado oil instead of butter or margarine
• Eat fish like salmon, mackerel, or sardines twice a week
• Snack on nuts, seeds, or avocado instead of chips or crackers
• Choose lean cuts of meat and remove visible fat
• Read ingredient labels and avoid anything with partially hydrogenated oil
• Limit processed foods, which often contain hidden saturated and trans fats

Does Coconut Oil Count as a Bad Fat?

This is a controversial topic. Coconut oil is about 90 percent saturated fat, which is higher than butter. But some people claim it is healthier because of its medium-chain triglycerides, or MCTs. The idea is that MCTs are metabolized differently and may not raise cholesterol the same way.

The evidence does not support this claim. A 2020 review in Circulation found that coconut oil raised LDL cholesterol significantly more than unsaturated oils like olive oil and canola oil. It did not show any clear benefit for heart health compared to other saturated fats.

Some small studies suggest that coconut oil may raise HDL cholesterol as well. But the rise in LDL is usually larger, which means the overall effect on heart disease risk is neutral or negative. The American Heart Association recommends against using coconut oil as a regular cooking fat.

If you enjoy the flavor of coconut oil, use it occasionally. But do not treat it as a health food. Olive oil and avocado oil are better choices for daily use.

What About Dietary Cholesterol in Eggs and Shrimp?

For decades, people were told to avoid eggs because of their cholesterol content. The thinking was that dietary cholesterol directly raised blood cholesterol. But research has since shown that dietary cholesterol has a much smaller effect on blood cholesterol than saturated fat does.

The 2015 Dietary Guidelines removed the previous limit of 300 milligrams of dietary cholesterol per day. The current advice is to eat as little dietary cholesterol as possible while following a healthy eating pattern. For most people, eating eggs in moderation is fine.

One large egg has about 186 milligrams of cholesterol but only 1.6 grams of saturated fat. The saturated fat content is what matters more. A study in the American Journal of Clinical Nutrition found that eating up to one egg per day was not associated with heart disease risk in healthy people.

Shrimp is another food that was once avoided for its cholesterol. It has about 166 milligrams of cholesterol per 3-ounce serving but almost no saturated fat. Research shows that shrimp does not raise LDL cholesterol in most people. The saturated fat content of the foods you eat with shrimp, like butter or creamy sauces, is the bigger concern.