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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.