Fats

What are fats?

Fats are a type of nutrient that you need to consume to live. While you might see a lot of references to fats that recommend leaving them off your plate, they aren’t all bad. In fact, some fats are essential, and your body won’t work properly without them.

Dietary fats are one of the four main types of nutrients (known as macronutrients). The other macronutrients are proteins, carbohydrates and water.

The main thing that sets fats apart is calorie density. Fats have the highest concentration of calories of any macronutrient. All fats, regardless of type, contain 9 calories per gram. That’s more than double the 4 calories per gram found in carbohydrates or proteins.

What fats do in your body

Fats belong to a type of lipid called triglycerides. Your body needs lipids, including fats, to do certain jobs. The walls of many of your cells are lipid-based. And lipids help store or carry things throughout your body more easily. Some key examples of that are the fat-soluble vitamins, A, D, E and K. Your body needs fat to use them properly.

Fat in your food helps activate your body’s feeling of satiety (pronounced suh-TY-eh-tee or SAY-she-uh-tee). That’s the feeling of satisfaction or fullness that tells you you’re no longer hungry and it’s time to stop eating.

The fats in your food don’t automatically turn into body fat (adipose tissue). Your body only stores fat if you take in more calories from protein, carbs or fats than your body needs to burn for energy.

What are the types of fats?

People often group fats into just two categories: saturated and unsaturated. But fats are more complicated than that. In reality, there are four types of dietary fats:

• Monounsaturated fats
• Polyunsaturated fats
• Saturated fats
• Trans fats

Monounsaturated fats

Also known as monounsaturated fatty acids (MUFAs), these mainly come from:

• Avocadoes and avocado oil
• Nuts and nut oils
• Olives and olive oil

Experts recommend that monounsaturated fats make up 20% or less of your total daily calories. At most, that’s 400 calories out of the recommended 2,000 calories per day.

Polyunsaturated fats

These are also known as polyunsaturated fatty acids (PUFAs). Some of these are essential, meaning your body can’t work properly without them. Your body also can’t make them, so you need to include them in your eating habits.

The essential polyunsaturated fatty acids are:

• Omega-3. People assigned male at birth (AMAB) need about 1.6 grams per day, while people assigned female at birth (AFAB) need about 1.1 grams per day.
• Omega-6. AMAB individuals need about 17 grams per day, while AFAB individuals need about 12 grams per day.

There are two main types of omega-3 fatty acids, each coming primarily from different sources:

• Long-chain. You can get these from fatty fish, especially herring, mackerel, salmon, sardines and trout, and mussels, a type of shellfish. They’re also found in breast milk (chest milk).
• Short-chain. These mainly come from plant and vegetable sources. Examples include leafy green vegetables, canola oil, flaxseed and flaxseed oil, soybeans, and walnuts and walnut oil.

There are many sources of omega-6 fatty acids. They include:

• Corn and corn oil
• Eggs
• Legumes like soybeans and soybean oil
• Sesame seeds and sesame seed oil
• Sunflower seeds and sunflower seed oil
• Softer types of margarine
• Wheat germ

Saturated fats

Saturated fats are solid at room temperature. In small amounts, they’re not harmful. Experts recommend that less than 10% of your daily calories come from saturated fats.

But research shows that saturated fats in excess can be bad for you. That’s because they may increase your risk of developing cardiovascular disease or heart disease. Experts suspect it has something to do with how they raise your LDL cholesterol. That’s one of the biggest reasons that experts strongly recommend limiting the amount of saturated fat you eat and how often you eat it.

The main sources of saturated fats include:

• Animal fats like tallow and lard
• Cocoa butter and chocolate
• Coconut milk and coconut oil
• Dairy, especially butter, cream, whole milk and certain cheeses
• Palm oil
• Red meats

Trans fats

Trans fats are a lot like saturated fats. The only real difference is a quirk of their chemical structure. Both are still solid at room temperature, and both raise your LDL cholesterol. But trans fats also lower your HDL cholesterol (also known as “good” cholesterol).

Trans fats can come from:

• Natural sources and processes. There are trace amounts of them in red meats and dairy fat. Tiny amounts also form when oils reach high temperatures.
• Artificial sources. Trans fats can be manufactured by processing liquid vegetable oils in certain ways.

But in many places around the world, including the United States, it’s illegal to make or add artificial trans fats to food products. That’s because of the long-term health risks from eating trans fats. And there’s evidence that links trans fats to increased risks of cancer and other health issues.

Are there good and bad fats?

Fats aren’t a simple good vs. bad situation (except for trans fats, which are always bad). Research shows many sources of saturated (sometimes called “bad”) fats don’t necessarily up your heart disease risk. Examples include whole-fat dairy, dark chocolate and unprocessed meats.

And while unsaturated — what some people call “good” — fats are beneficial and you need them, you can still have too much of a good thing. That’s why experts recommend you limit the amount of unsaturated fats in your meals and snacks.

Is low-fat automatically better?

No, not always. Reducing the amount of fat in something often changes the way it tastes (often making it less tasty). To offset that, it’s common for food manufacturers to put more sugar and carbs into “low-fat” foods to make them taste better. But sugar and carbs, over time, can increase your risk of developing conditions like Type 2 diabetes.

To protect yourself from trading one unwanted thing for another, it’s important to read nutrition labels. Pay close attention to the amounts of carbs and sugars in the product.

And if you have questions, talk to your primary care provider. They may be able to offer resources and guidance to help you better understand how to get the best out of what you eat. They might also be able to connect you to other experts, like dietitians or nutritionists, who can help you.

Is there such a thing as a high-fat diet?

Some diets put a bigger priority on fat and protein than on carbohydrates. One example would be a ketogenic diet. This kind of diet is helpful for certain conditions, like treatment-resistant epilepsy, but it isn’t for everyone. For some people, a keto diet can put too much strain on their liver or kidneys. So, you shouldn’t try a keto diet without first talking to a primary care provider.