Fat is a chemical compound containing one or more fatty acids essential to keep the body healthy. Along with protein and carbohydrates, it is one of three nutrients that supply calories to the body. Oils are simply liquid fats and the two terms are often used interchangeably.

Dietary fat is an important component of good health. In addition to providing energy, fat delivers essential nutrients such as fat-soluble vitamins and essential fatty acids. Fats and oils also add flavor and texture to foods, as well as increasing a person’s sense of fullness after a meal.

Fats and oils are classified into three major groups depending on their chemical structure: saturated, unsaturated (including polyunsaturated and monounsaturated) and trans fat (chemically altered fats found in manufactured or processed foods). The fats found in foods are almost always a mixture of these groups of fatty acids.

While fats play an important role in good health, they also can damage health when consumed in large amounts. Different types of fats have varying effects upon a person’s health. Polyunsaturated and monounsaturated fatty acids (e.g., fish oils, olive oil) have been shown to have a protective effect on cardiovascular health. Meanwhile, saturated fats and trans fats contribute to health problems in people who consume them at high levels. However, all fats are energy dense, providing 9 calories per gram, more than twice the 4 calories per gram of proteins and carbohydrates.

Eliminating fat completely from one’s diet can lead to a deficiency of essential fatty acids, which can result in negative health consequences. Instead, people are urged to include dietary fats in balance with other nutrients to meet daily energy needs and to achieve a healthy body weight.

In particular, emphasis should be placed on lowering saturated fats consumption and minimizing or eliminating trans fats.

Fat is a chemical compound containing one or more fatty acids that is essential to keeping the body properly functioning. Along with protein and carbohydrates, it is one of three types of nutrients that supply calories to the body. Fat provides 9 calories per gram, more than double the amount provided by protein and carbohydrates. Oils are simply liquid fats and the two terms may be used interchangeably.

Fat provides numerous benefits to the body. In the body, fats provide energy, as well as insulation and protection. Fat is involved in the processes that help regulate blood pressure, heart rate, blood vessel constriction, blood clotting and the functions of the nervous system.

Dietary fat also provides flavor and texture to foods. For example, fat may make foods creamy (e.g., peanut butter and ice cream), moist and tender (e.g., meat) or brown and crispy (e.g., baked goods).

Consuming fat provides people with a sense of fullness, because fat is digested more slowly than proteins and carbohydrates. This sense of fullness – or satiety – may keep people from overeating.

However, too much fat – particularly too much of certain types of fat – can be bad for a person’s health. People who consume excess fat are at risk of obesity, which can contribute to many diseases, including heart disease, diabetes and other chronic conditions.

A diet high in certain types of fat can also significantly raise the level of low-density lipoprotein (LDL) cholesterol, the so-called “bad” cholesterol. The type of fat that a person consumes is as important to health as the overall total amount of fat consumed.

Fats and oils are made up of chains of molecules called fatty acids. These fatty acids can be classified into three major groups depending on their chemical structure: saturated, unsaturated (including polyunsaturated fatty acids and monounsaturated fatty acids) and trans fat (chemically altered fatty acids in manufactured or processed foods). The fats and oils found in foods are almost always a mixture of these groups of fatty acids.

Fats are made of fatty acids (chains of carbon, hydrogen and oxygen) and glycerol (three-carbon alcohol that forms the backbone of fatty acids). Most fat is stored in the body as triglycerides, which circulate in the blood along with cholesterol. (The term “triglycerides” can also refer to the common form of fat in foods as well as the body.)

The major types of fat include saturated fats, unsaturated fats and trans fats. All fats and oils contain both saturated and unsaturated fatty acids. Fats are classified as either saturated or unsaturated depending on the percentage of fat that is dominant. For example, butter contains mostly saturated fat as well as lesser amounts of unsaturated fat. As a result, it is classified as a saturated fat. Meanwhile, canola oil has a high percentage of monounsaturated fat, as well as smaller amounts of polyunsaturated and saturated fats. It is classified as a monounsaturated fat.

The two major types of healthy fats are both unsaturated. These fats reduce levels of low-density lipoprotein (LDL) cholesterol, the so-called “bad” cholesterol. The two major types of unsaturated fats are:

• Monounsaturated fats. A form of unsaturated fat that is missing one pair of hydrogen atoms in the carbon chain, forming one double bond. Extra hydrogen atoms can be inserted chemically, which is why they are called “unsaturated.” These fatty acids are found mostly in foods from plant origin, have a lower melting point and are usually liquid at room temperature, but start to solidify at refrigerator temperatures. Monounsaturated fats not only lower levels of “bad” cholesterol, but also raise the levels of high-density lipoprotein (HDL) cholesterol, which has health benefits. Sources of monounsaturated fats include canola, olive and peanut oils, and avocados.
  
  

  

• Polyunsaturated fats. An unsaturated fat that is missing more than one pair of hydrogen atoms in the carbon chain. The presence of more double bonds between the carbon atoms lowers the melting point even more than monounsaturated fats. Polyunsaturated fatty acids are highly unstable and are more susceptible to rancidity than saturated and monounsaturated fats, especially after prolonged contact with oxygen, light, or heat. Found in foods from plant origin and from fish, polyunsaturated fats can be further divided into two sub-groups depending on the location of the first double bond along the carbon chain: omega-6 fatty acids and omega-3 fatty acids. Polyunsaturated fats are found primarily in oils from plants, including sesame and sunflower seeds, corn and soybeans, many nuts and seeds and their oils, as well as fatty fish such as salmon.

The two major types of unhealthy fats include:

• Saturated fats. Fats in which every available site along each carbon chain is filled with a hydrogen atom. Saturated fatty acids are found mainly in animal fats (e.g., butter, lard, whole milk) and certain plant fats (e.g., coconut oil, palm oil, cocoa butter). They have a high melting temperature because of their chemical structure and are solid or hard at room temperature.
  
  
• Trans fats. A form of unsaturated fat in which hydrogen atoms are added during a process called hydrogenation. Trans fatty acids are mainly manufactured fats that are stable and solid at room temperature. Trans fats are found in deep-fried foods, margarines, baked goods and other processed foods made with “hydrogenated” or “partially hydrogenated vegetable oils.” Some trans fat is found naturally in small amounts in various meat and dairy products.

These subtle chemical differences between the types of fats are responsible for their very different properties and effects in the body. Diets high in saturated fats and trans fats increase low-density lipoprotein (LDL) or “bad” cholesterol levels and, therefore the risk of heart disease, whereas most unsaturated fats have harmless or even helpful effects on blood cholesterol.

All fats are a mixture of saturated, polyunsaturated and monounsaturated fatty acids. However, the dominant form of fatty acid determines which of these categories a fat belongs to. For example, olive oil, safflower oil and canola oil are high in monounsaturated fat content and are considered to be monounsaturated fats. Meanwhile, butter, animal fats, and tropical oils such as palm oil and coconut oil are high in saturated fat content and are considered to be saturated fats.

Despite the widespread attention given to the negative consequences of fat intake, it is an important and essential component of a healthy diet. It is unhealthy to eat a diet that is completely fat-free. Fat provides energy for the body and is used in the production of cell membranes and in compounds called eicosanoids. These compounds are similar to hormones and help regulate blood pressure, heart rate, blood vessel constriction, blood clotting and the nervous system.

Dietary fat provides the body with essential fatty acids. These fatty acids are necessary for good health but are not made by the body and can only be obtained through food. Essential fatty acids help control blood pressure, blood clotting, inflammation and other body functions. The most important essential fatty acids are linoleic acid (found in vegetable oils and poultry fat) and alpha-linolenic acid (found in soy oil, nuts and seeds). These essential fatty acids aid in the growth and development of infants, keep the brain and nervous system functioning properly and help maintain healthy skin.

Fat helps transport fat-soluble vitamins (vitamins A, D, E and K) from food into the body. Fat promotes healthy hair and skin, protects vital organs, insulates the body and provides a sense of fullness after meals (satiety). It is stored in the body as triglycerides in fat (adipose) tissue.

Other important roles that fat plays in the body include:

• Provides a storehouse for the body’s extra calories.
• Serves as part of all cell membranes.
• Present in the skin to repel water.
• Makes up part of material that insulates nerves and enhances nerve conduction.

A lack of fat in the diet can stunt the growth and development of infants and children. People of all ages who lack fat in their diets may not fully absorb fat-soluble vitamins, depriving them of the benefits that help smooth the skin, protect vision, strengthen the immune system and keep reproductive organs functioning properly.

However, different types of fats have varying impacts upon a person’s health. For instance, polyunsaturated and monounsaturated fatty acids (e.g., fish oils, olive oil) have been shown to have a protective effect on heart health. They lower levels of both total blood cholesterol and low-density lipoprotein (LDL) cholesterol, the so-called “bad” cholesterol. Meanwhile, monounsaturated fats raise the levels of high-density lipoprotein (HDL) cholesterol, which has health benefits.

By contrast, saturated fats and trans fats can contribute to health problems in people who exceed recommended levels. These types of fat cause the liver to produce more LDL or “bad” cholesterol, which is associated with a greater risk of atherosclerosis (hardening of the arteries). Higher levels of saturated fats are also associated with increased risk of stroke and certain types of cancer. (However, saturated fats are also associated with increased level of HDL or “good” cholesterol.)

One recent study found that consuming just one piece of carrot cake high in saturated fat along with a milkshake can prevent the body’s HDL cholesterol from protecting the inner lining of the arteries from agents that promote hardening of the arteries.

Trans fats have the same negative effects on blood cholesterol as saturated fats. In addition, they are associated with a decrease in the levels of high-density lipoprotein (HDL).

Therefore, consumers should watch out for “low cholesterol” or “no cholesterol” products that are high in saturated fats or trans fats because they can still be dangerous to a person’s health.

Health experts recommend finding the right nutritional balance for optimal health. Dietary fat provides more than twice the calories found in carbohydrates or proteins. Excessive amounts of calories can lead to obesity, which also increases the risk of many health problems.

Some negative health effects previously attributed to high-fat diets have lately come under scrutiny. For example, recent research indicates that high-fat diets may not be associated with breast cancer and colon cancer. However, links between high-fat diets and other forms of cancer (including prostate cancer) still appear to be valid.

Certain fats are essential for humans. Eliminating all sources of fat can lead to a deficiency of essential fatty acids, which can result in negative health consequences.

Many people reduce the fat in their diets to lose weight, help control diseases such as diabetes and improve heart health. In response to consumer demand, manufacturers have developed low-fat food products.

Although these products are lower in fat content, they are not necessarily lower in  calories. In fact, many manufacturers increase the sugar and carbohydrate content of these foods to enhance the taste lost through eliminating fats. The end result is that many people who purchase low fat products reduce fat without lowering their calorie intake.

The calories consumed in excess of the body’s needs are mainly stored as fat (adipose) tissue. This can lead to excessive weight gain and obesity. It can also contribute to high blood cholesterol, coronary artery disease and other medical problems.

People should consume fats in moderation. Consuming large amounts of any type of fat – including unsaturated fat – results in excess calories and can lead to weight gain. In particular, emphasis should be placed on lowering saturated fats and minimizing or eliminating trans fat intake. These should be replaced with polyunsaturated and monounsaturated fats.

The Food and Nutrition Board recommends that total dietary fat intake should make up 20 to 35 percent of the total daily energy (calorie). Saturated fats and/or trans fats should be less than 10 percent of total daily calorie intake; polyunsaturated fats should be up to 10 percent of total calorie intake and monounsaturated fats up to 20 percent of total calories.

Overall, trans fats should be minimized to the lowest possible level in one’s diet. People at risk for heart disease should limit saturated fat to less than 7 percent of total calories each day. The Food and Drug Administration's (FDA) Food Guide Pyramid is a useful tool for monitoring daily food intake.

Other tips for lowering levels of unhealthy fats and overall fat content include:

• Use unsaturated oils whenever possible. For example, use olive oil instead of butter to sauté, and use olive oil instead of vegetable oil in salad dressings and marinades. Use canola oil when baking.
  
  
• Try to avoid foods that are likely to be high in trans fats. These include french fries, doughnuts, cookies, crackers and other processed foods. Especially avoid commercially fried foods and commercially baked goods.
  
  
• Sprinkle slivered nuts or sunflower seeds on salads as a substitute for bacon bits.
  
  
• Snack on nuts instead of potato chips or crackers. Use nonhydrogenated peanut butter or other nut-butter spreads on celery, bananas, rice or popcorn cakes. When choosing processed foods, choose foods made with unhydrogenated oil rather than hydrogenated or saturated fat.
  
  
• Use low-fat types or skim the fat off homemade broth or stock before using in recipes.
  
  
• Add avocado instead of cheese to a sandwich.
  
  
• Substitute fish for meat once or twice a week. Fish such as salmon and mackerel are rich in monosaturated fats and omega-3 fats.

An oil recently introduced to the United States may offer unique health benefits when compared to other oils. Diacylglycerol (DAG) is based on diglyceride, while all other oils on the market are based on triglycerides. DAG oil is metabolized in a way that less fat is stored in the body. DAG oil is a good source of polyunsaturated and monounsaturated fats. DAG oil is derived from soy and canola oil.

DAG oil has a light, mild flavor that does not change the taste or texture of foods and it can be used for baking, sautéing, frying and as a part of salad oils.

DAG oil is not a fat substitute. It contains the same calories and fat as conventional oils, but is metabolized differently in the body.

Consumers can also choose fat substitutes. Fat substitutes added to baked or commercial foods mimic the desirable qualities of fat without adding as many calories. They can be classified into three categories based on their nutrient source: carbohydrate-based, protein-based and fat-based fat substitutes. Although fat substitutes on the market are considered safe by the FDA, their long-term benefits and safety are not known.

Preparing questions in advance can help patients to have more meaningful discussions regarding their conditions. Patients may wish to ask their doctor or registered dietitian the following questions related to fats & oils:

1. How will I know if I am eating too much fat?
   
   
2. What are the long-term health threats I face from fat?
   
   
3. Where can I find help planning a diet that is low in saturated and trans fats?
   
   
4. What are some cooking tips for reducing levels of saturated and trans fats in meals?
   
   
5. How much saturated and trans fat can I safely eat?
   
   
6. How can I ensure that my child eats a diet that has enough fat for growth while not being too high in saturated and trans fats?
   
   
7. How can I make sure my child’s school lunches are low in saturated and trans fats?
   
   
8. Can you recommend good products that use healthy ingredients as substitutes for saturated and trans fats?
   
   
9. Are there any tests that can tell me if I am eating too much fat?
   
   
10. I know that unsaturated fats are healthy, but how will I know if I am eating too many of them?
    
    
11. Should I have my blood cholesterol levels tested?