What is dietary fat?

Dietary fat refers to the fats and oils found naturally in animal and plant foods, and those used in cooking, at the table, and added to processed foods. Dietary fat is made up of fatty acids. Fatty acid can be defined as a carboxylic acid with a long aliphatic chain and most naturally occurring fatty acids have an unbranched chain of an even number of carbon atoms, from 4 to 28.

Dietary fat has five important functions:
*As a dietary source of energy
*For cell structure and membrane functions
*As a source of essential fatty acids for cell structures and prostaglandin synthesis
*As a vehicle for oil-soluble vitamins
*For control of blood lipids

Fat also contributes to the palatability of food and is important in cooking and food processing.

There are 2 types of fatty acids: saturates and unsaturated, which based on how the molecules in the fatty acid are joined together. All fats contain both saturated and unsaturated (mono- and polyunsaturated) fatty acids but are sometimes described as ‘saturated’ or ‘unsaturated’ according to the proportions of fatty acids present.

Dietary guidelines from the World Health Organization and the Dietary Reference Intakes recommend a total fat intake between 20 and 35% of total calories. The minimum of 20% is to ensure adequate consumption of total energy, essential fatty acids, and fat-soluble vitamins. This is to prevent atherogenic dyslipidemia (low high-density lipoprotein cholesterol (HDL-C), high triglyceride-rich lipoproteins) which occurs with low-fat, high carbohydrate diets and increases risk of coronary heart disease.
What is dietary fat?

Fat in human body

Fat is an essential nutrient, which contributes approximately 30-45% of food energy in western diets. In technical they are referred to as lipids.

Fats have physical, chemical and physiologic properties that make them important in nutrition. In addition to fats ingested as food, there are specific lipids synthesized by the human body that are essential to life.

Fat along with proteins and carbohydrates, one of the three nutrients are used as energy sources by the body.

Energy is one of the principal nutritional requirements of man and fat is a principal source of the energy. Each grams of fat consumed supplies the body with 9 calories worth of energy. Fat is composed of glycerol and one to three fatty acids and serves as a key energy source from many cells in the body.

In addition, certain fatty acids can play a regulatory role in the body by serving as precursors for eicosanoids.

Meanwhile cholesterol is a lipid substance that plays as structure role in cell membranes and is a precursor for steroid hormones.

The layer of fat is not evenly distributed throughout the body. In men it is generally concentrated in the chest, accentuating the profile of the cleft below the pectoral area; in the chin; in the stomach and in the buttocks.

In the women, fat tends to the shape of the breast, the chin, the stomach, the thighs and especially the area around the pelvis and up to the end of the gluteus muscles.  In males, of the total body mass it constitutes 3%, whereas it amounts to about 20% of the total body fat. In case of females, it is 30% of the body fat and about 9% of the body mass.
Fat in human body

Waxes of lipid

Simple lipids containing 3-carbon alcohol glycerol linked to one to three fatty acids or their derivatives. 

Examples of simple lipids are triglycerides, steroids, wax ester and waxes.

A wax is a complex, varying mixture of lipids with long fatty acid tails bonded to long chain alcohols or carbon rings.

The molecules pack tightly, so the result substance is firm and water repellent. Waxes in the surface of apples and other fruits from temperate zones are solids or semisolids pates, consisting of terpenes, ceryl cerotate, ceryl palmitate and other esters.

Waxes dissolved in fat solvents, and their solubility is dependent on temperature. Waxes are totally insoluble in water, a consequence of their hydrocarbon, non-polar, nature. They can wet and disperse pigments and can be emulsified with water which makes them useful in the furniture, pharmaceutical and food industries. 

The role of waxes is to protect the surface of plant leaves, stems and seeds from dehydration and infections by microorganisms.

Waxes also present in fish oils, especially in sperm whale blubber and whale head oil, which contain a ‘reservoir’ of spermaceti wax.
Waxes of lipid

What are triglycerides?

Triglycerides are nothing but fats. Animal fats and plants oil are triglycerides. Triglycerides are triesters of glycerol and long chain carboxylic acids called fatty acids.

Although some of the molecules contain three identical fatty acids, in most cases, two or three different acids are present.

More than ninety-nine percent of the fats that people consume are triglycerides. Less than one percent that is left out is cholesterol.

Triglycerides circulate in the blood stream and provide a source of energy. Compared with other energy-yielding macronutrients, triglycerides represent the body’s richest source of energy.

When there are excess triglycerides in circulation, there is an increased risk of a heart attack.

One gram of triglycerides will give 9 calories to the body. The usual blood level of triglycerides is 40-160 mg/100 ml of blood.

Triglycerides are the major energy store that maintain during deprivation. This is true of all mobile animals and because fat is light in relation of its energy yield, it is essential for hibernation and migration.
What are triglycerides?