1. Fats: A Concentrated Energy Source
Chapter 6
Fats:
A Concentrated Energy Source

2. What Are Lipids
You are familiar with the word fat, but the word lipid may be new. Lipid is a broader term for a group of compounds that includes fats, oils, lecithin, and cholesterol.
Lipids can be grouped into three main classes:
Triglycerides
Phospholipids
Sterols

3. Triglycerides
Triglycerides are the major type of fat found in foods and in the body. They consist of three fatty acids attached to a glycerol molecule.
Fatty acids are organic compounds made up of a chain of carbon atoms to which hydrogen atoms are attached.

4. Saturated and Unsaturated
Fatty acids can be saturated or unsaturated.
Saturated fatty acids have no double bonds in their chemical structure. They have a full load of hydrogen atoms.
Unsaturated fatty acids have at least one double bond between two carbon atoms in each molecule.
The number of double bonds and hydrogen atoms determines the degree of saturation.
One double bond means monounsaturated fatty acid
Two or more double bonds means polyunsaturated fatty acid.

5. Fat facts
Nearly all fats and oils contain a mixture of the three types of fatty acids. For instance, corn oil is 13% saturated, 25% monounsaturated, and 62% polyunsaturated.
The fats in meat and dairy products, including beef fat, lard, butterfat, tend to be high in saturated fatty acids.
Fats from plants are usually higher in unsaturated fatty acids. Olive and peanut oils are high in monounsaturated fatty acids. Corn, safflower, and soybean oils are high in polyunsaturated fatty acids.

6. More fun fat facts
The prevalent type of fatty acid determines whether a lipid is liquid or solid at room temperature. Lipids that are high in saturated fatty acids tend to be solid at room temperature. Lipids that are high in unsaturated fatty acids tend to be liquid at room temperature.
This is because unsaturated fats have a lower melting point than more highly saturated fats.

7. Hydrogenation
Unsaturated fatty acids can be hydrogenated . Hydrogenation is the process of breaking the double carbon bonds in unsaturated fatty acids and adding hydrogen. This process converts liquid oils into solid fats. For instance, hydrogen is added to some of the double bonds in unsaturated liquid vegetable oil to make solid margarine.
This process also improves the oils keeping quality. Oils turn rancid if exposed to oxygen for prolonged periods.

8. Trans-fatty acids
Trans-fatty acids are formed when oils are partially hydrogenated. Some of the unsaturated fatty acids in the oil change their molecular shape. Research shows that trans-fatty acids act much like saturated fats in the body. They have been linked to increased risk of heart disease and certain types of cancer.

9. What Is Unhealthy About Trans Fats?
Unfortunately, as it turns out (and as we were relatively slow to learn), trans fats increase total cholesterol levels and LDL cholesterol levels; worse (and in contrast to saturated fats), they reduce HDL cholesterol levels. Trans fats also appear to interfere with the body's usage of omega-3 fatty acids, which are important for heart health.
In other words, trans fatty acids are bad for cardiovascular health.

10. Which Is Worse - Saturated Fats or Trans Fats?
Both. Saturated fats and trans fatty acids are bad for you. Saturated fats are almost always found in foods that also contain cholesterol, so saturated fats offer a "one-two" punch to heart health. On the other hand, trans fatty acids not only increase LDL cholesterol, they also decrease HDL cholesterol. While nobody can say yet definitively which is worse, it does appear that both are bad.

11. Other lipids
Phospholipids are lipids that have a phosphorus containing compound in their chemical structure.
Lecithin is a phospholipid. Lecithin is made by the liver so it is not essential to the diet. Lecithin is found in many foods, including egg yolks. You will also find it in the ingredient list of some food products. Soya lecithin is added to baked goods and chocolate candy.
Lecithin is an emulsifier, meaning that it can mix with water and fat. This is why adding an egg yolk to oil and vinegar will form a mixture and not separate. (mayonnaise)

12. Sterols
Sterols are the third class of lipid. Sterols have a complex molecular structure. They include some hormones, vitamin D, and cholesterol.
Cholesterol is a white, waxy lipid made by the body that is part of every cell. Your body uses cholesterol to make sex hormones and bile acids.
Cholesterol is found only in animal tissues. It is never present in plants, therefore, peanut butter, corn oil margarine and similar plant products contain no cholesterol.

13. Function of Lipids
Lipids serve many important functions in the body. You need a number of fatty acids for normal growth and development. Your body can make most of these. However, two polyunsaturated fatty acids, linoleic acid and linolenic acid, are called essential fatty acids. You must get these from your diet.
If your diet is missing these nutrients, the skin, reproductive system, liver, and kidneys may all be affected.

14. More about the function of fat
The body stores a large share of lipids in adipose tissue. About half of this tissue is just under your skin. It serves as an internal blanket that holds in body heat.
Body fat surrounds organs, such as the heart, and liver. This fat acts like a shock absorber. It helps protect the organs from the bumps and bruises of body movement.
Vitamins A, D, E, and K dissolve in fat and are carried into the body in the fat in food that you eat.

15. Lipid Digestion and Absorption
Most of the fat we eat are triglycerides.
Fat separates from the watery contents of the stomach and floats on top.
When fat reaches the small intestine, it mixes with bile, which acts as an emulsifier. Bile helps break fats into tiny droplets and keeps them suspended in watery digestive fluid. Breaking the fat into tiny droplets increases its surface area, making it easier for pancreatic enzymes to break triglycerides down into glycerol, fatty acids, and monoglycerides.
Bile improves the absorption of fat by the cells lining the intestine.

16. Fats and heart Health
Fats in the diet and in the body play a major role in the health of your heart. Coronary heart disease (CHD) refers to disease of the heart and blood vessels. It’s the leading cause of death in the United States and the second leading cause of death in Canada.
Fatty compounds made up mostly of cholesterol can attach to the inside walls of arteries, forming a buildup called plaque. The gradual buildup of plaque is called atherosclerosis.

17. The uncontrollable heart health risk factors
Unfortunately, you cannot control some factors that greatly affect your state of health.
Age
Gender
Race
Family history

18. Controllable heart health risk factors
It is possible to decrease your chances of CHD or heart attach.
Smoking
High blood pressure
High blood cholesterol
Diabetes
Excess weight
Inactivity
Stress

19. Fats and Cancer
Cancer is a general term that refers to a number of diseases in which abnormal cells grow out of control. Many factor may contribute to the development of cancer, diet is one of those factors. High fat diets may contribute to the development of colon, prostate, breast, and some other types of cancer.