The type of fat you eat every day, over a lifetime, can help keep you healthy. Eating fats found in seafood or from most plant sources is linked to lower risks of heart disease, diabetes and obesity when compared with diets high in fats from animal sources or highly processed foods.
Why does the body need fat?
Fat helps the body function. It can be a source of energy, and it helps the body use vitamins and other nutrients. The fat you eat also plays a role in hormone production and in how the body's cells are made and work.
Types of fat
When you eat fat, your body breaks it into smaller parts called fatty acids. These fall into two categories: saturated and unsaturated fatty acids.
Saturated fats have a stiff chemical structure and are often solid at room temperature. Foods that have saturated fats include lard, beef tallow, meat, and dairy foods such as whole milk, butter, some cheese and yogurts. Coconut oil and palm oil also are high in saturated fats.
Unsaturated fats have a more flexible chemical structure. When separated from food, they are often liquid at room temperature. Unsaturated fats can be either monounsaturated or polyunsaturated. Omega-3 and omega-6 fatty acids are polyunsaturated.
Examples of unsaturated fats include:
- Avacados and avocado oils.
- Olives and extra-virgin olive oil.
- Nuts, such as almonds, cashews, peanuts and hazelnuts.
- Seeds, such as flaxseed, hemp seed and chia seed.
- Soybeans, edamame and tofu.
- Safflower, sunflower and corn oil.
- Canola, soybean, flaxseed and walnut oil.
- Seafood, such as shrimp, salmon, anchovies, sardines and tuna.
Trans fats naturally occur in meat and dairy products from grazing animals. But most trans fats in food come from plant oils that are chemically changed to be semisolid fats. This process is called partial hydrogenation.
Trans fats are often found in processed foods, such as fast food, commercial baked goods, stick margarine and foods that are deep fried. This type of fat is less expensive than other fats and gives food a long shelf life.
In the United States, trans fats cannot be used in food production. Food makers in other countries may still use this ingredient.
Fats and health
Fat is a healthy part of the diet when it's balanced with carbohydrates, protein and the needs of your body. Your age, sex, activity level, and if you're pregnant or breastfeeding can change the amount of fat and other nutrients you need.
Two fatty acids, the omega-6 linoleic acid and the omega-3 alpha-linolenic acid (ALA), are needed for the body but must come from the diet. You can find ALA and linoleic acid in walnuts, flaxseed, chia seed and soybean products.
Some experts suggest that in a healthy diet, no more than about 30% of calories should come from fat.
Fat and disease
Fat is one piece of a healthy eating pattern that can lower your risk of disease. The type of fat you choose, your diet and lifestyle all affect your risk of heart disease.
For heart-healthy choices on fats and oils:
- Cut out trans fats that are artificially created. Trans fats raise levels of blood cholesterol linked to heart disease, called low-density lipoprotein (LDL). Trans fats also lower blood cholesterol levels that helps keep the heart healthy, called high-density lipoprotein (HDL).
- Limit saturated fats, even if you are healthy. (8) Replace foods high in saturated fat with nuts, seeds, avocados, fish, and plant oils from fruits, seeds or nuts.
Some health guidelines suggest saturated fat should be less than 10% of your calories. For example, if you have a 2,000-calorie diet, 10% is 22 grams of saturated fat a day. For people with risk factors for heart disease, the American Heart Association suggests less than 6% of your total calories come from saturated fat.
Choosing unsaturated fats in place of saturated fats can improve blood cholesterol, which may lower your risk of heart disease.
When it comes to cancer prevention, your overall diet matters more than just fat. A higher risk of cancer seems to come from diets that are high in animal fats and processed meat, as well as sugar.
A lower cancer risk is linked to diets focused on plant foods, including plant protein sources such as legumes, as well as fish or poultry. Diets that help prevent cancer tend to have more unsaturated fats than saturated fats.
Diets that focus on plants, where unsaturated fats are more common than saturated fats, also tend to be linked to:
- Lower inflammation levels.
- Better blood glucose control.
- Less damage to DNA.
- Higher numbers of healthy gut bacteria.
Overall, eating fats from seafood or from plant sources is often linked to lower levels of disease. But it is just one factor. Other diet choices, such as fiber intake, and lifestyle choices, such as physical activity, play a role in disease development.
Should you choose low-fat or fat-free foods?
Products with fat removed can be healthy. But check the nutrition label. Foods that have been processed to remove fat may have added sugars. These products haven't been shown to help with health goals, such as weight or blood glucose management, or overall heart health.
Reading labels
In the United States, the Nutrition Facts panel on a product calls out the total fat in each serving. Under total fat amount, you will see amounts listed for saturated fat and trans fat, even if the amount is zero. You also may see amounts listed for polyunsaturated fats or monounsaturated fat.
For saturated fat, aim for less than 2 grams per serving. Saturated fats can add up quickly in foods that combine ingredients, such as meat and dairy products. Examples are tacos, cheeseburgers and Cobb salad. Baked goods with butter, full-fat ice cream and other desserts are also popular sources of saturated fats. Look at serving sizes and saturated fat amounts in the Nutrition Facts panel on products or menus when you're planning a treat or meals.
In the ingredient list, items that have "partially" in the name likely contribute trans fats to the product. Examples are partially hydrogenated palm oil or partially hydrogenated sunflower oil. Trans fats found naturally in meat or dairy won't be listed separately.
Baked goods, snack crackers or chips, and fried items commonly have ingredients with saturated fats in the United States and trans fats where those ingredients are still used.
How do you get started replacing saturated fats with unsaturated fats?
Focus on getting more plants in your diet. Instead of butter or lard, use plant-based oils such as extra-virgin olive oil.
Other ways to work healthy fats into the diet include:
- Add fish to your diet, especially oily fish such as trout and salmon.
- Choose lean meat and skinless poultry. Trim visible fat from meat. Remove fat and skin from poultry.
- Eat and drink low-fat dairy products.
- Eat nuts, seeds and nut butters.
- Limit processed foods, which often have saturated fat.
Keep your calorie limit in mind as you shift from saturated fats to unsaturated fats. Dietary fat is important for health, but it's equally important to get the recommended amounts of fruits, vegetables, legumes and whole grains in your diet. These foods are rich in vitamins, nutrients and fiber.
