Fats

Fat or Lipid can be defined as:

1. Any of a group of organic compounds that are greasy to the touch, insoluble in water, and soluble in alcohol and ether: lipids comprise the fats and other esters with analogous properties and constitute, with proteins and carbohydrates, the chief structural components of living cells.

2. Any of a group of organic compounds, including the fats, oils, waxes, sterols, and triglycerides, that are insoluble in water but soluble in nonpolar organic solvents, are oily to the touch, and together with carbohydrates and proteins constitute the principal structural material of living cells. (American Heritage Dictionary).

So the main thing about lipid is that it a substance that is greasy, insoluble in water but soluble in organic substances and constitute the principal structural material of living cells together with carbohydrate and protein.

The main functions of lipid are?

The lipids of physiological importance for humans have four major functions:
1. They serve as structural components of biological membranes.
2. They provide energy reserves, predominantly in the form of triacylglycerols.
3. Both lipids and lipid derivatives serve as vitamins and hormones.
4. Lipophilic bile acids aid in lipid solubilization.

Lipids are grouped in 4 main division:

-Triacylglycerides
-Phospholipids
-Plasmalogens
-Sphingolipids

Lipids play diverse and important roles in nutrition and health. Many lipids are absolutely essential for life, however, there is also considerable awareness that abnormal levels of certain lipids, particularly cholesterol (in hypercholesterolemia) and, more recently, fatty acids with trans fatty acids, are risk factors for heart disease amongst others.

We need fats in our bodies and certain types in our diet. Animals in general use fat for energy storage because fat stores 9 KCal/g of energy. Plants, which do not require energy for movement, can afford to store food for energy in a less compact but more easily accessible form, so they have evolved use starch (a carbohydrate, not a lipid) for energy storage.

Furthermore, lipids can be stored in an anhydrous form whereas carbohydrates typically cannot, which means that anhydrous lipid stores about 6 times as much energy per weight as hydrated carbohydrates. As an example, a typical 70 kg man would have to weigh approximately 125 kg if his energy stores were converted from triacylglycerol to glycogen.

One need not think that fat and lipids are the same thing this is because fat is actually is a subgroup
of lipid.

So here we will discuss fat or fatty acids more as this has the more impact on human body and health.

Fatty acids fill two major roles in the body:
1. as the components of more complex membrane lipids.
2. as the major components of stored fat in the form of triacylglycerols.

Chemically, fatty acids can be described as long-chain monocarboxylic acids the saturated examples of which have a general structure of CH3(CH2)nCOOH. The length of the chain usually ranges from 12 to 24, always with an even number of carbon atoms. When the carbon chain contains no double bonds, it is a saturated chain. If it contains one or more such bonds, it is unsaturated. The presence of double bonds reduces the melting point of fatty acids.

So points that you should know Saturated Fatty acids contains NO double bonds, Unsaturated Fatty acids have double bonds..this makes the difference because the presence of double bonds appear to lower the melting points of lipids and makes the lipid easier to disintegrate (metabolised). Therefore, Unsaturated Fatty acids are Healthier!

Our body can make its own fats, except these two type of fats which are the highly unsaturated fatty acids know as linoleic acid and linolenic acid. Our body cannot make that fats and thus we call it Essential Fatty acids. We have to acquire them from plant-based diet, because plant is the one who makes them.

Fatty acids are stored for future use as triacylglycerols in all cells, but primarily in adipocytes of adipose tissue. Triacylglycerols constitute molecules of glycerol to which three fatty acids have been esterified. The fatty acids present in triacylglycerols are predominantly saturated. The major building block for the synthesis of triacylglycerols, in tissues other than adipose tissue, is glycerol


Fats eaten by human will be metabolised to give energy. In fact, fats are the MAIN source of energy giver and acts as insulator of heat. This explains why fatter person tends to feel more at ease in cold situation.

Unused fats will be deposited or stored in the skin, the covering of the heart, the inner lining of bloodvessel among others. and this pose health complication if the deposit exceeds normal level.

One thing to note, among the synthesis factor for fatty acids is Acetyl-coA. Acetyl-CoA is the end product of carbohydrate metabolism.Therefore, even though one eats sweets instead of other heavy carbohydrates or fats. the possibility of getting fat is still there..so be wise, be moderate in everything.

HEALTH EFFECTS DUE TO EXCESSIVE FAT

Cholesterol is a blood fat needed by the body in moderate amounts. However, high cholesterol levels can lead to atherosclerosis and coronary artery disease (CAD). Angina is chest pain caused by the restriction of blood flow to the heart (cardiac ischemia). Nitrates may be used to relieve angina.