Dietary fat: Know which to choose

Dietary fat is the fat that comes from food. The body breaks down dietary fats into parts called fatty acids that can enter the bloodstream. The body also can make fatty acids from the carbohydrates in food.

The body uses fatty acids to make the fats that it needs. Fats are important for how your body uses many vitamins. And fats play a role in how all cells in the body are made and work.

But all dietary fats are not the same. They have different effects on the body. Some dietary fats are essential. Some increase the risk for disease, and some help prevent disease.

Find out how different dietary fats affect your body and how to choose foods with healthier fats.

Types of fat

There are two main kinds of dietary fats: saturated fat and unsaturated fat. These terms describe the chemical makeup of the fatty acids.

Most foods have a mix of different kinds of fat. But some have higher levels of saturated fats, and others have higher levels of unsaturated fats. Key differences in fats include the following:

Saturated fats. Saturated fats are usually solid at room temperature. The most common sources of saturated fats are meats and dairy products.
Unsaturated fats. Unsaturated fats are usually liquid at room temperature. Vegetable oils, nuts and fish have mostly unsaturated fats. There are two types of unsaturated fats: monounsaturated and polyunsaturated.

Saturated fats in food

The Dietary Guidelines for Americans suggest that less than 10% of calories a day should be from saturated fats. The American Heart Association suggests a goal of 5% to 6% of daily calories from saturated fats.

Foods high in saturated fats include:

Foods baked or fried using saturated fats.
Meats, including beef, lamb, pork as well as poultry, especially with skin.
Lard.
Dairy products like butter and cream.
Whole or 2% milk.
Whole-milk cheese or yogurt.
Oils from coconuts, palm fruits, or palm kernels.

Saturated fats can add up quickly in foods that combine ingredients. In U.S. diets, the most common sources of saturated fats are sandwiches, burgers, tacos and burritos — foods that usually combine meat and dairy products. Baked goods with butter, full-fat ice cream and other desserts are also common sources of saturated fats.

Saturated fat tends to raise levels of cholesterol in the blood. Low-density lipoprotein (LDL) is called "bad" cholesterol. High-density lipoprotein (HDL) is called "good" cholesterol. Saturated fats raise the levels of both.

A high level of bad cholesterol in the bloodstream increases the risk heart and blood vessel disease.

Limited evidence suggest that saturated fats and high cholesterol levels may be linked to an increased risk of Alzheimer's disease or other diseases that cause dementia.

Monounsaturated fats in food

Monounsaturated fats are found in many foods, including red meats and dairy products. About half the fats in these foods are saturated and half monounsaturated.

Many plants and plant oils are high in monounsaturated fats but low in saturated fats. These include:

Oils from olives, peanuts, canola seeds, safflower seeds, and sunflower seeds.
Avocadoes.
Pumpkin seeds.
Sesame seeds.
Almonds.
Cashews.
Peanuts and peanut butter.
Pecans.

Monounsaturated fats from plants may lower bad cholesterol and raise good cholesterol. They also may improve the control of blood sugar levels.

Replacing saturated fats with monounsaturated fats in the diet may lower the level of bad cholesterol and triglycerides in the blood. Triglycerides are fat cells that circulate in the bloodstream and are stored in the body’s fat cells. A high level of triglycerides in the blood increases the risk of diseases of the heart and blood vessels.

Eating plant foods high in monounsaturated fats, particularly extra virgin olive oil and tree nuts, may benefit heart health and blood sugar regulation.

Polyunsaturated fats in food

The two categories of polyunsaturated fats are omega-6 fatty acids and omega-3 fatty acids.

Omega-6. Sources of omega-6 fatty acids include:

Corn oil.
Cottonseed oil.
Peanut oil.
Soybean oil.
Sunflower oil.

Benefits of a diet high in omega-6 fatty acids, especially when they replace saturated fats, may be linked to:

Lower bad cholesterol.
Lower triglycerides.
Higher good cholesterol.
Better blood sugar control.

Omega-3. Sources of omega-3 fatty acids include oily fish, seeds and nuts:

Fish such as salmon, anchovies, mackerel, herring, sardines and tuna.
Oils from canola seeds, soybeans, walnuts and flaxseed.
Soybeans.
Chia seeds.
Flaxseed.
Walnuts.

Diets high in omega-3 fatty acids may have health benefits, including:

Lowering levels of triglycerides in the blood.
Lowering the risk of heart and blood vessel diseases.

Trans fats in food

Trans fats are a type of fat that raises bad cholesterol and lowers good cholesterol. There are very small amounts of naturally occurring trans fat in meats and dairy from grazing animals, such as cows, sheep and goats.

But most trans fats are in plant oils that have been chemically changed to be a solid fat. These are called partially hydrogenated oils. At one time, trans fat oils were thought to be a healthy choice to replace saturated fats. They also were inexpensive and a had a long shelf life.

The U.S. Food and Drug Administration determined that artificially created trans fats are "no longer recognized as safe" in foods. They are no longer used in U.S. food production. They may still be used in other countries.

How can I start eating healthier?

A healthy diet is a balance between taking in enough calories and nutrients for your level of activity. Your health care provider or a dietician can help you understand goals for calories, nutrients and types of foods to eat.

One thing to consider is that each gram of fat has 9 calories. That's true for all fats. So calories can add up quickly, even with healthy fats. For example, walnuts are a healthy snack high in polyunsaturated fats. But just a dozen walnut halves contain about 160 calories — more calories than in one large apple.

The key message about fats is to focus on eating healthy fats and limiting unhealthy fats. Eat more fruits, vegetables, legumes, nuts, seeds and whole grains that are rich in vitamins, nutrients and fiber.

Try these tips to reduce unhealthy fat in your diet:

Use plant-based oils instead of butter or lard. For example, saute vegetables with olive oil instead of butter. Use canola oil for hot cooking, such as searing or stir frying.
Add fish to your diet, especially oily fish.
Choose lean meat and skinless poultry. Trim visible fat from meat. Remove fat and skin from poultry.
Eat and drink low-fat dairy products.
Reach for whole fruits and vegetables when you're hungry.
Limit processed foods, which often contain saturated fat.
Check labels on low-fat or fat-free processed food, which may have lots of added sugars and sodium (salt).