Dietary fats: Know which types to choose
When choosing fats, pick unsaturated fat over saturated fat. Here's how.By Mayo Clinic Staff
You don't need to eliminate all fat from your diet. In fact, some fats actually help promote good health. But it's wise to choose the healthier types of dietary fat and then enjoy them — in moderation.
The facts about fat
There are numerous types of fat. Your body makes its own fat from taking in excess calories. Some fats are found in foods from plants and animals and are known as dietary fat. Dietary fat is a macronutrient that provides energy for your body.
Fat is essential to your health because it supports a number of your body's functions. Some vitamins, for instance, must have fat to dissolve so they can be used by your body.
But fat is high in calories. If you eat more calories than you need, you will gain weight. Excess weight is linked to poor health. In addition, some types of dietary fat are thought to play a role in cardiovascular disease.
Research about the possible harms and benefits of dietary fat is always evolving. And a growing body of research suggests that when it comes to dietary fat, you should focus on eating healthy fats and avoiding unhealthy fats.
Harmful dietary fat
There are two main types of potentially harmful dietary fat:
- Saturated fat. This is a type of fat that comes mainly from animal sources of food, such as red meat, poultry and full-fat dairy products. Saturated fat raises total blood cholesterol levels and low-density lipoprotein (LDL) cholesterol levels, which can increase your risk of cardiovascular disease. Saturated fat may also increase your risk of type 2 diabetes.
- Trans fat. This is a type of fat that occurs naturally in some foods in small amounts. But most trans fats are made from oils through a food processing method called partial hydrogenation. These partially hydrogenated trans fats can increase unhealthy LDL cholesterol and lower healthy high-density lipoprotein (HDL) cholesterol. This can increase your risk of cardiovascular disease.
Most fats that have a high percentage of saturated fat or that contain trans fat are solid at room temperature. Because of this, they're typically referred to as solid fats. They include beef fat, pork fat, butter, shortening and stick margarine.
Healthier dietary fat
The types of potentially helpful dietary fat are mostly unsaturated:
- Monounsaturated fatty acids. This is a type of fat found in a variety of foods and oils. Studies show that eating foods rich in monounsaturated fatty acids improves blood cholesterol levels, which can decrease your risk of heart disease. Research also shows that these fatty acids may benefit insulin levels and blood sugar control, which can be especially helpful if you have type 2 diabetes.
- Polyunsaturated fatty acids. This is a type of fat found mostly in plant-based foods and oils. Evidence shows that eating foods rich in polyunsaturated fatty acids improves blood cholesterol levels, which can decrease your risk of heart disease. These fatty acids may also help decrease the risk of type 2 diabetes.
- Omega-3 fatty acids. One type of polyunsaturated fat is made up of mainly omega-3 fatty acids and may be especially beneficial to your heart. Omega-3, found in some types of fatty fish, appears to decrease the risk of coronary artery disease. There are plant sources of omega-3 fatty acids. However, it hasn't yet been determined whether replacements for fish oil — plant-based or krill — have the same health effects as omega-3 fatty acid from fish.
Foods made up mostly of monounsaturated and polyunsaturated fats are liquid at room temperature, such as olive oil, safflower oil, peanut oil and corn oil.
Fish high in omega-3 fatty acids include salmon, tuna, trout, mackerel, sardines and herring. Plant sources of omega-3 fatty acids include flaxseed (ground), oils (canola, flaxseed, soybean), and nuts and other seeds (walnuts, butternuts and sunflower).
Recommendations for fat intake
Because some dietary fats are potentially helpful and others potentially harmful to your health, it pays to know which ones you're eating and whether you're meeting recommendations.
The 2015-2020 Dietary Guidelines for Americans offers the following recommendations about dietary fat intake:
- Avoid trans fat.
- Limit saturated fat to less than 10 percent of calories a day.
- Replace saturated fat with healthier monounsaturated and polyunsaturated fats.
Be aware that many foods contain different kinds of fat and varying levels of each type. For example, butter contains unsaturated fats, but a large percentage of the total fat is saturated fat. And canola oil has a high percentage of monounsaturated fat but also contains smaller amounts of polyunsaturated and saturated fat.
What changes should I make to my diet?
Focus on replacing foods high in saturated fat with foods that include monounsaturated fats and polyunsaturated fats.
But a word of caution — don't go overboard even on healthy fats. All fats, including the healthy ones, are high in calories. So consume monounsaturated and polyunsaturated fats instead of other types of fat, not in addition to them.
Here are some tips to help you make over the fat in your diet:
- To avoid trans fat, check food labels and look for the amount of trans fat listed. By law a serving of food containing less than 0.5 grams of trans fat can be labeled as 0 grams. Therefore, it's important to also check ingredient lists for the term "partially hydrogenated."
- Use oil instead of solid fats. For example, saute with olive oil instead of butter, and use canola oil when baking.
- Prepare fish, such as salmon and mackerel, instead of meat at least twice a week to get healthy omega-3 fatty acids. Limit sizes to 4 to 6 ounces of cooked seafood a serving, and bake or broil seafood instead of frying.
- Choose lean meat and skinless poultry. Trim visible fat from meat and poultry, and remove skin from poultry.
- Snack smart. Many popular processed snack foods are high in fat, especially solid fats. Be sure to check food labels for saturated fat. Better yet, snack on whole fruits and vegetables.
What about very low-fat diets?
If watching fat content is a good strategy, is it even better to try to eliminate all fat from your diet? No.
First, your body needs some fat — the healthy fats — to function normally. If you try to avoid all fat, you risk getting insufficient amounts of fat-soluble vitamins and essential fatty acids.
Also, in attempting to remove fat from your diet, you may wind up eating too many processed foods touted as low-fat or fat-free rather than healthier and naturally lower fat foods, such as fruits, vegetables, legumes and whole grains. Instead of doing away with fat in your diet, enjoy healthy fats in moderation.
Feb. 02, 2016
See more In-depth
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- Paniagua J, et al. A MUFA-rich diet improves postprandial glucose, lipid and GLP-1 responses in insulin-resistant subjects. Journal of the American College of Nutrition. 2007;26:434.
- AskMayoExpert. Fish oil. Rochester, Minn.: Mayo Foundation for Medical Education and Research, 2015.