Fats are essential constituents of macronutrients. There are several different types of dietary fat and some are much safer than others.
Fat is important to a variety of body functions. It is a source of energy, and protects the nerves and the skeleton. Fat helps other nutrients to do their work, too.
Not all dietary fats however are equally beneficial:
- Saturated and trans fats can raise cholesterol levels and increase disease risk.
- Unsaturated fats support health and may be monounsaturated or polyunsaturated.
Meats, milk products, foods for snacks and baked goods contain saturated and trans fats. Many unsaturated— safe— sources of fats include nuts, oils, beans, and avocados.
Below, we look in-depth at the different types of fats, including which are most safe and which foods contain them.
What are fats?
Fats are classified in a range of ways, depending on their attributes:
- Fats or fatty acids: These terms can refer to any type of fat, but “fats” usually describes those that are solid at room temperature.
- Lipids: This can refer to any type, regardless of whether it is liquid or solid.
- Oils: This can describe any fat that is liquid at room temperature.
- Animal fats: Among these are butter, cream, and fats in meats, such as lard.
- Vegetable fats: Among these are the fats in olives and avocados, as well as olive, peanut, flaxseed, and corn oils.
In humans and many other animals fats are an important part of the diet. The body stores fat in energy, warmth and safety.
All fats have the same amount of calories— 9 calories pergram— compared with less energy-dense carbohydrates and proteins, at about 4 calories per gram, regardless of the type.
Different types of fat have different influences on health, particularly blood and heart health.
The following sections take a closer look at the effects of different fats on the body.
At room temperature, saturated fats are solid, and are often called solid fats. These fatty acids have the basic carbon structure “saturated” with hydrogen atoms.
Saturated fat can increase health risks if a person consumes too much over a long period of time.
A high intake of saturated fat can eventually raise cholesterol levels in the body that are low-density lipoprotein (LDL). This in turn increases the risk of stroke and cardiovascular disease.
American Heart Association AHA recommends that people eat no more than 13 grams of saturated fat per day.
Some sources of saturated fat include:
- animal meats and meat products
- dairy products, except those that are fat-free
- processed foods, including baked goods, snack foods, and french fries
- some vegetable oils, including coconut oil, palm oil, and cocoa butter
Research suggests replacing saturated fat in the diet with refined carbohydrates or sugar, which are also bad for health, is not safe.
A person should instead substitute saturated fat sources with healthier foods, such as nuts, seeds, avocados, beans, whole grains, and vegetables.
Unsaturated fats at room temperature are liquid and are mostly derived from plant oils. These are considered “healthy” fats by health care professionals.
The two main types of unsaturated fat are:
Monounsaturated fat molecules are not filled with atoms of hydrogen-each fat molecule has a single atom of hydrogen.
Monounsaturated fats can reduce LDL, or “poor,” cholesterol levels, and maintain “healthy” high-density lipoprotein (HDL) cholesterol levels in good health.
Simply adding monounsaturated fat to the diet will not have this effect, however, unless a person also reduces their saturated fat intake.
Many health professionals agree that a diet rich in monounsaturated fats can also reduce the risk of heart disease a person may face. There is plenty of monounsaturated fats in the Mediterranean diet, which research suggests may reduce the risk of chronic illness.
Sources of monounsaturated fats include:
- olives and olive oil
- nuts and nut butters
Numerous spaces are not filled with hydrogen atoms around each polyunsaturated fat molecule.
Nutritionists report that polyunsaturated fats are good for health, especially those from fish and algae, known as polyunsaturated fatty acids called omega-3.
The Office of Dietary Statistics says omega-3 acids will help keep the heart healthy, minimize blood triglycerides and improve the health of the brain, joints and eyes.
Omega-3 fatty acids can protect against heart disease by reducing levels of blood cholesterol and, potentially, inflammation.
That said, a large-scale analysis of Cochrane found that the omega-3 supplements had no significant heart health benefits. It will require more research to determine the results with certainty.
The omega-6 fatty acids are the other form of polyunsaturated fats. Which occur mostly in processed foods and vegetable oils.
An excessive intake of omega-6, typical in American standard diets, can lead to increased inflammation.
Sources of polyunsaturated fats include:
- oily fish, such as sardines, mackerel, trout, salmon, and herring
- safflower, grapeseed, soybean, and sunflower oils
- nuts, seeds, and pastured eggs
Trans-fats are made. They are the result of a process which adds hydrogen to liquid vegetable oils in order to make them stronger. The partially hydrogenated oils are another term for trans fats.
Trans fats are not necessary, and have harmful effects on health.
Trans fats increase LDL cholesterol levels, and lower HDL cholesterol levels. This increases the risk of diabetes, stroke and type 2 heart disease.
Each year the World Health Organization (WHO) reports that trans fats are associated with 500,000 cardiovascular deaths.
Trans fats became common when they were found easy to use by food companies, and cheap to manufacture. They also have a long shelf life and can give a nice taste to food.
Because trans fats can be used several times over in commercial fryers, these have become popular in fast-food chains and other restaurants.
But the WHO has called on governments to exclude trans fats from global food supply. Most of the commercial food manufacturers have now eliminated trans fats from their products.
Sources of trans fats can include:
- fried foods, such as french fries
- doughnuts, pies, pastries, biscuits, and other baked goods
- pizza dough, cookies, and crackers
- stick margarines and shortenings
- packaged foods
- fast foods
If any ingredient list includes “partially hydrogenated oils” on food packaging, this means the product contains trans fats.
The AHA recommends that consumption of trans fats should not exceed 5–6 percent of the total caloric intake of a person. Eating any amount of these fats however increases health risks.
Dietary fat recommendations
According to the WHO, to avoid unhealthy weight gain:
- total fat intake should be less than 30% of total caloric intake
- saturated fat intake should be less than 10% of total caloric intake
- trans fat intake should be less than 1% of total caloric intake
Health professionals consider using monounsaturated and polyunsaturated fats to replace saturated and trans fats. In general, the diet should be nutritionally adequate and should contain sufficient calories to maintain a healthy weight.
Not all fats benefit equally. It’s important to understand the distinctions between fat types, carefully read labels and make healthy dietary choices.