Introduction

Fat stores in the human body perform a number of vital roles; they provide protection for the vital organs and warmth in extreme conditions. In exercise fats supply an almost unlimited supply of energy for the average individual. Unless you are a sumo wrestler there is absolutely no reason why you need to carry or eat excess amounts of fat in your daily diet.

What are the main roles of fat in the body?

• It is a primary energy source providing 70% of our total energy requirements at rest
• Vital organs are supported, cushioned an protected by it
• Fat soluble vitamins gain entry into the body and are transported via fat
• Body heat is preserved by it

Good or bad fat

Saturated or unsaturated fats

Saturated fats are saturated with the maximum amount of hydrogen and are usually solid at room temperature. Saturated fats occur mostly in animal products such as meats, milk, butter, lard and cheeses. The problem however does not stop there as many processed foods including, biscuits, pastries, cakes and puddings are also made from these fat sources. Saturated fatty acids have long been considered the villain behind heart disease as they can increase your cholesterol levels. It is recommended that these form a maximum of 10% of your total calorific dietary intake.

Unsaturated fats (also referred to as monounsaturated) contain less hydrogen and tend to be liquid at room temperature. They can be found in such sources as olive, rapeseed, nuts, seeds and avocados and they are generally found in plant sources. It is these fats that are said to provide the greatest health benefits as they have been shown to reduce total cholesterol levels. Two sources that plant fat source theory are coconut and palm kernel oil, both of which are extremely high in saturated fat. These fats can make up approximately 15% of your total calorific dietary intake.

Good Fat Sources / Low Saturated Fat content

Bad Fat Sources / High Saturated Fat content

Fats and Exercise

Fats as an Energy Source

1g of fat provides 9 Kcals of energy compared to protein and carbohydrates that provide only 4 Kcals of energy.
Fats are broken down in the body into fatty acids and triglycerides. Fatty acids are stored as adipose (fat) tissue, or they circulate in the blood as free fatty acids (FFA). Triglycerides are stored in the muscles. These substances can produce ATP through chemical reactions and are a secondary energy source for muscular activity.

During endurance type training (i.e. 90 mins or longer) fat can provide an essential energy source and help delay the onset of fatigue.
One of the main adaptations of endurance type exercise is an increased ability to use fat as an energy source. It is an increase in FFA in the blood that provides this energy source however this does not occur by simply eating more fat.

It is true that some foods, especially those containing caffeine have been shown to increase fat usage during exercise by increasing FFA utilisation. Some studies have shown that the ingestion of caffeine (link) 60 minutes prior to exercise can increase duration by increasing fat mobilisation from the body's fat stores as an energy supply.

It is therefore fairly true to say that those individuals that partake in any regular form of activity will become more efficient at using their fat stores as an energy source than those who adopt for a more sedentary lifestyle.

Fats and Oils - Technical

Well-fed animals build surplus food energy for future use by making and storing fats in their bodies. Plants store fats and oils in their seeds and fruits. Fats and oils from plants and animals are chemical compounds called esters, combinations of glycerin with various fatty acids.
The Earth supplies the mineral oil called petroleum. Most of the compounds present in petroleum are hydrocarbons. These resemble esters in some ways. However, since most of the uses of animal and vegetable fats and oils depend on the fact that they are esters, petroleum cannot usually be substituted for them.
At ordinary temperatures fats are solids and oils are liquids. They are much alike in chemical makeup and food value. When a fat or oil combines with oxygen, it releases a great amount of energy. Plants and animals release this energy slowly for use in their cells. If fats or oils are burned as fuels, the energy is released much faster in the form of heat and light.
Fats and oils can be stored in living tissues because they do not dissolve in the watery liquids that surround them. Both plants and animals depend on this waterproof property for protection of their storehouses of fat and oil.
Plants and animals use their stored fats and oils for energy in time of need. People and other animals also eat fats and oils. Weight for weight, fats and oils supply more than twice the energy given by carbohydrates. Portions not used immediately for energy may be saved in the form of body fat or the carbohydrate glycogen. Some fats and oils are used as shortening to enrich foods, particularly bread, cakes, and pastry. Many oils are eaten as salad dressings and as part of fried foods.

The uses of specific kinds of fats and oils are determined by their properties. Fats and oils that are suitable for food do not change rapidly when exposed to air. They spoil gradually, as bacteria attacks them with enzymes, and they become rancid. Certain vegetable oils called drying oils are most valuable in paints and varnishes. The major drying oil is linseed oil, which comes from flax.
Because a diet high in fat has been associated with heart disease and other health problems, fat substitutes, or fake fats, have been developed by food manufacturers to replace natural fats in certain products. In February 1990 the Food and Drug Administration (FDA) approved the first fat substitute in the United States, Simplesse, made from milk protein and blended egg whites, for use in frozen desserts and baked goods. Experimental fat substitutes awaiting FDA approval include Stellar, Olestra, and Trailblazer.

How Chemical Processes Change the quality

The most abundant of the fatty acids combined in fats and oils are called stearic, palmitic, and oleic. Compounds having only one acid are called stearin, palmitin, and olein. Beef tallow is rich in stearin and palmitin, which are solids at room temperature; olive oil is mostly olein, a liquid. Most vegetable fats and oils contain all three of these acids. Small quantities of various substances, including other fatty acids, give fats and oils their distinctive odours and flavours.
Fats and oils are unsaturated or saturated, depending on the way in which carbon atoms are bonded together in their molecular structure. Unsaturated oil can be made saturated by applying heat and pressure to the oil in an atmosphere of hydrogen. This process, called hydrogenation, is used to change vegetable oils to solid fats for making margarine and cooking fats. This however turns the once good fat of vegetable oil into a saturated fat.