Fat

Fat

The name fat may make it sound like something you shouldn't eat. But fat is an important part of a healthy diet. Fat from your diet gives you energy. As a bonus, fat in food helps you feel full, so you don't eat too much.

Some foods, including most fruits and vegetables, have almost no fat. Other foods have plenty of fat. They include nuts, oils, butter, and meats like beef.

The lipids are a heterogeneous group of substances found in plant and animal tissues, which share the property of being relatively insoluble in water, and soluble in organic solvents, such as ether, chloroform and benzene. Fat contain 9 kcal per gram.

Functions of fats

·  They are the chief energy stores of the body, which form an important source of energy during starvation or other emergencies.

·  Fats play a role in the absorption of fats soluble vitamins like vitamins A, D, E and K.

·  Fats are the constituents of cell membrane structure and regulate the membrane permeability.

·  Subcutaneous fat acts as an insulator and helps in retaining body heat.

·  Fats are important as cellular metabolic regulators (Steroid hormones and prostaglandin).

Fat is the main energy store in the body and the most concentrated source of energy in the diet – 1 g of fat provides 37kJ (9Kcal), more than double that provided by either protein or carbohydrate (4Kcal).

Classification of lipids

Lipids are classified into 4 categories as follows:

I. On the basis of chemical composition

II. On the basis of sources

Fats are divided into 2 types based on their source, namely visible and invisible fats.

III. On the basis of fatty acids

IV. On the basis of requirement

Fatty acids are of 2 types:

Essential fatty acids: Fatty acids which are essential to be taken in our diet because they cannot be synthesized in our body are known as essential fatty acids. (eg.) Linoleic, linolenic and arachidonic acids.

Non-essential fatty acids: Non-essential fatty acids are those which can be systhesized by the body and which need not be supplied through the diet. Palmitic acid, oleic acid and butyric acid are examples of non-essential fatty acids.

Digestion, absorption and storage metabolism

Fats are not digested in the stomach. Fats delay emptying of the stomach. Fats are hydrolyzed by the pancreatic and intestinal lipases in the intestines into diglycerides, monoglycerides and fatty acids. Bile is essential for the digestion and absorption of fats.

Storage of fats

Fat is stored in the adipose tissues. In normal human beings adipose tissue constitutes of 10 – 15% of the body weight.

Fat metabolism

Fatty acids  are  oxidized by certain enzymes in the tissues to carbon dioxide and water. The oxidation takes place through the tricarboxylic acid cycle.       

Deficiencies

Over consumption

·               Over weight

·               Obesity

·               Coronary heart disease

·               Cancer

·               High cholesterol