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Fats: What You Need To Know

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Fats: What You Need To Know









With all of the media hype around Fats, it is no wonder that they have a bad reputation. They have been linked with heart disease, obesity, and other threats to health. What are fats, what does the body do with them, and are they really necessary?

Fats are one of the three substances, alongside proteins and carbohydrates that make up the bulk of the human diet. Fats are important for other reasons, too. They make food more palatable. For example, think of the difference between dry and buttered toast, or salad with and without salad dressing. They are also the most energy-rich of all foods. For example, 3 ½ ounces (99 g) of bread supplies about 250 calories. The same weight of butter, which is 80 percent pure fat; provides 720 calories (Jacoby and Youngson, 2005).

What are fats?


About 90 percent of the fats people eat are known as neutral fats. They are made up of two chemicals—fatty acids and glycerol—which are both formed from carbon, hydrogen, and oxygen. Fatty acids and glycerol form molecules called triglycerides.

These fats can be either saturated or unsaturated, depending on the structure of the fatty acids. Fatty acids consist of chains of linked carbon atoms, with hydrogen atoms linked to each carbon atom. Any carbon atom can link to four other atoms and is thus said to be capable of making four bonds. A carbon atom in a fatty-acid chain will use two of its bonds to link to adjacent carbon atoms (Maton et al, 1993). If it is also linked to two hydrogen atoms, so that the four bonds are used up, it is said to be saturated. However, if it links to only one hydrogen atom, there will be a spare bond, and a double bond will form between it and the next carbon atom. In this case it is said to be unsaturated. So fatty acids with only single bonds between the carbon atoms are saturated fatty acids, and those with one or more double bonds are unsaturated. Most saturated fats are solid at room temperature, and unsaturated fats are liquid (Maton et al, 1993). This happens because most saturated fats are from warm-blooded animals, whose fat is just about liquid at their body temperature, which is above that of their surroundings. Unsaturated fats tend to be from fish and plants that are adapted for life at much lower temperatures (Cavendish, 2004). 


What fat is best?


Saturated fats have a bad reputation because of their association with cholesterol, which makes up 10 percent of the fat people eat. It is not a true fat, because its structure is different from that of fat, but it is usually found with saturated fat. This means that the more saturated fat people eat the more cholesterol they eat.

The body needs cholesterol for a range of functions, from maintaining brain tissues to making sex hormones, but the body can make all the cholesterol it needs in the liver. The extra cholesterol taken in when saturated fat is eaten seems to interfere with the body's cholesterol-controlling mechanism, and the bloodstream becomes flooded with it. Surplus cholesterol, combined with other fats, becomes deposited on the walls of the blood vessels and can lead to arterial and heart disease. This is why doctors recommend changing from eating saturated fats that are high in cholesterol to unsaturated ones low in cholesterol (Jacoby and Youngson, 2005).

How the body uses fats


Fats make up part of the wall surrounding everybody cell. The body uses fats to insulate it against cold, to store reserve energy, to absorb shock around bones and organs, to insulate nerve cables, to lubricate skin, and to help transport vitamins.

The digestive system breaks down fats into fatty acids and glycerol. The fatty acids are then broken down further to release energy for immediate use. Any excess is reconverted to triglycerides and stored in the cells under the skin and around the internal organs. The glycerol is converted into glycogen, which is either broken down at once to release energy or stored in the liver until it is needed. Once the liver's glycogen storage system is full, the glycogen is changed into fat and stored in the body cells. If an excess of fat is stored there, it makes a person overweight. That is why it is important not to eat more than is needed (The Columbia Encyclopedia, 2013). 

Burning up fats


Hormones from the thyroid, adrenal, and pituitary glands control the rate at which the body burns up fats for energy. At times of stress or during intense physical activity, the hormones adrenaline and noradrenalin have a rapid effect on the rate of fat breakdown, increasing the amount of fatty acids in the blood by as much as 15 times, and pushing up the cholesterol level. If the fatty acids are burned up in exercise, they do no harm; but if they remain in the body, they can, with the cholesterol, lead to a fatty buildup in the arteries. This is one reason why exercise is a good way of dealing with stress.

Some studies that have examined the eating habits of large numbers of people have linked a high-fat diet (mainly triglycerides) with an increased risk of certain cancers, especially cancers of the colon, prostate, and breast. High-fat diets may also be linked to obesity and cardiovascular disease.

People who eat many specific saturated fatty acids (12 to 16 carbon atoms long) are more likely to develop clogged arteries and heart disease than people who eat fewer saturated fatty acids. However, stearic acid, an 18-carbon saturated fatty acid in animal fat, does not appear to be harmful (Jacoby and Youngson, 2005). By reducing their intake of saturated fatty acids, people can lower their chances of developing heart disease. One way to cut down on saturated fatty acids is to eat monounsaturated and polyunsaturated fatty acids instead. Fish oils containing long chain (20- and 22-carbon) omega-3 polyunsaturated fatty acids may reduce triglyceride levels in the blood, so people who eat one or two servings of fish each week may lower their chances of developing heart disease. Barry Swanson, professor of food science and nutrition at Washington State University, says omega-3s appear to protect the heart by making blood platelets less likely to clot. Recent studies have also reported a possible protective effect for eye diseases. Foods rich in omega-3 fatty acids include fish like tuna, salmon, mackerel and herring, plus flax seeds or oil, and walnuts. Some scientists believe that omega-3fatty acids may also help to prevent the development of inflammatory diseases such as rheumatoid arthritis and asthma (Burmeier, 2006).



Cavendish, M. (2004). Encyclopedia of Life Sciences. Volume: 5. (Ed 2) Marshall Cavendish Publishing: Tarrytown, NY.

Burmeier, B. The Facts on Fats: Read the Labels, because they’re Not All Bad! E. Magazine. Volume: 17. Issue: 2 Publication date: March-April 2006.

Jacoby, D.B. and Youngson, R.M. (2005). Encyclopedia of Family Health. Volume: 12. (Ed 3): New York.

Maton, A and Hopkins, J and McLaughlin, J.W. and Johnson, S. and Warner, M.Q. and LaHart, D. and l Wright, J.D. (1993). Human Biology and Health. Englewood Cliffs, New Jersey, USA: Prentice Hall.

The Columbia Encyclopedia (2013). Fats and Oils. (6th Ed). The Columbia University Press.




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