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Fats

Fats are the most concentrated source of energy in diet.

Fats are solid at room temperature (20 degrees celcius). They are called oils if they are liquid at 20 degrees celcius.

Sources

Animal fats: Butter, milk, cheese, eggs, fat of meat and fish, ghee

Vegetable fats: Oils of plant seeds like groundnut, mustard, sesame, cocount etc. (properly called vegetable oils rather than vegetable fats).

Other sources: small quantities of fat are found in most other foods such as cereals, pulses, nuts and vegetables. Rice and wheat have 3% fat in them, each. Hence, large cereal consumption provides considerable amounts of invisible fat.

Even if a diet is deficient in fat, our body has got the special ability to convert excess carbohydrate into fat for storage purposes.

Functions

Provide energy (9 Calories per gram)

By providing energy, fats spare proteins from being used up for energy. This is called protein-sparing effect of fat.

Fats serve as vehicles for fat soluble vitamins (vitamins A, D, E, and K).

Fat beneath the skin keeps us warm in cold weather.

Fat deposited around internal body organs protects them like a cushion.

Fat imparts better taste to food. Remember the difference in taste between a boiled potato and fried potato?

Vegetable oils are rich sources of Essential Fatty Acids (see below).

Fat Requirements

Fats (visible + invisible fats) should provide no more than 30% of total calories in the diet. If you need 2400 calories in a day, for example, then fat in your diet should provide not more than 800 calories in it.

At least half of this total fat intake should consist of vegetable oils. They are rich in Essential Fatty Acids with numerous positive effects to health.

The lower the fat intake, the lesser the risk of coronary heart disease.

Visible and invisible fats

Visible fats are those that have been separated (and hence concentrated) from their natural sources. For example, butter is obtained from milk. Such fat can easily be quantitated and hence its caloric value is easy to calculate.

On the other hand, the invisible fats are those that are present in their natural sources (for example, we talked about 4% fat in wheat and rice). Such invisible fat is present in almost every food. Their contribution to diet cannot be calculated accurately.

The major contribution to diet comes from invisible fats. Visible fats are of a limited value.

Hydrogenated fats

It is a process in which hydrogen is added to the vegetable oils under optimum temperature and pressure in the presence of a catalyst. The process renders liquid oils into semisolid or solid fats. The main advantage of hydrogenation is that the fat is able to maintain its quality in hot and humid climates. Such hydrogenated fat is a very popular cooking medium in India.

The disadvantage of hydrogenation is that the unsaturated fatty acids are converted into saturated acids and the Essential Fatty Acid content is drastically reduced. The vitamin content undergoes a reduction too. It is therefore advisable (and mandatory in many countries) to fortify such hydrogenated fat with Vitamins A and D.

Refined Oils

Refining of oils is usually done by treatment with steam, alkali etc. This process removes the free fatty acids and other rancid materials, thereby improving the palatability (taste).

Refining does not bring about any change in the Unsaturatty fatty acid content of the oil. It only improves the quality and taste of oils. Quite understandably, refined oils are costlier than their natural counterparts.

Diseases caused by Fat

Obesity: A diet rich in fat can encourage obesity and thus endanger the health. Obesity poses multiple threats to the health, and can be measured easily by Body Mass Index (BMI).

Phrenoderma: Deficiency of essential fatty acids in the diet leads to a rough and dry skin, a condition called phrenoderma (Toad Skin). Phrenoderma is characterised by rough rash like eruptions on the back and sides of arms and legs, the back, and the buttocks. It can be cured by giving linseed of safflower oil which are rich in Essential Fatty Acids.

Coronary Heart Disease: High fat intake (particularly the saturated fat), is one of the major risk factors leading to coronary heart disease. LDL (Low density lipoprotein) and VLDL (Very low density lipoprotein) are harmful, while HDL (High density lipoprotein) protects against Coronary heart disease. The higher the intake of essential fatty acids in diet, the lower the risk of developing (and dying from) Coronary heart disease.

Cancer: High dietary fat intake can increase the chances of developing breast and colon cancers.

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This page last updated on:
October 15, 2003