Fat nutrient definition and its Role in human diet

fat nutrient definition


There are 6 major ingredients present in food that control the growth, strength, and survival of the body known as nutrients. All of these nutrients increase the performance of the human body by being involved in various physiological functions, help the organism to perform its basic function, and to maintain good health. The body gets nourished in a healthy way when all these nutrients are in the right proportions. This article is about the fat nutrient definition and its role of fat in the humans diet as we all know that one of these nutrients is fat or lipid (3) & (4).

What is fat?

Fat or lipid is a major component of the human diet, it is an organic compound that is made up of a combination of carbon, hydrogen, and oxygen. Like carbohydrates, fats do not contain hydrogen and oxygen. Fats are triesters of glycerol and fatty acids. At normal temperatures, fats can be solid or liquid depending on molecular structure and composition. Fat provides a good amount of energy to the body as 1 gm of fat provides 9 kcal of energy (1).

Properties of Fat

1. Fat is a micronutrient and does not contain hydrogen and oxygen in a ratio of 2:1.

2. Glycerol and soap are produced when fat substances are boiled for a while in an aqueous solution of alkali or washing soda.

3. Lipids or fats are insoluble in water because fats are lighter than water. Soluble in solutions of ether, alcohol, benzene, chloroform, acetone, etc

4. As the molecular weight of fats increases, their melting point increases.

5. Some lipids are solid at normal temperature and some lipids are liquid at 20° hence called oil.

6. At the end of the hydrolysis process, fats are converted into fatty acids and glycerol (6).


Fat is divided into different parts.

  • Based on the origin, there are two types of fats

1. Vegetable oil

Fat produced from different oilseeds is called vegetable oil examples are mustard oil, coconut oil, sesame oil, almond oil, etc.

2. Animal fat

Animal fat is produced from animals, the example of these types of fats is lard, suet, ghee, butter, egg yolks, animal and various fish liver oils, etc.

  • Based on the structure fats are three types

1. Simple fat

An ester composed of three molecules of fatty acids and one molecule of glycerol is called a simple fat it is also called triglyceride. It does not contain any non-fat substance.

2. Compound fat

When simple fat combined with other organic or inorganic compounds are called compound fats.

Fat + carbohydrates → glycolipids

Fat + protein → lipoprotein

3. Derivative fat

Fats that are formed as a result of hydrolysis of simple or compound fats are called fats. Such as steroids, turpentine, carotenoids, etc.

  • Based on the number and position of double bonds in the constituent fatty acids fat is divided into two types.

1. Saturated fat

Saturated fats are mainly found in animals in which carbon atoms are bound together in a single bond. Saturated fat has a bad impact on health. It is solid at normal temperature. An example of these types of fats is palmitic acid, stearic acid, etc. (3).

2. Unsaturated fat

Unsaturated fats found in plants in which carbon atoms are bound together in double bonds. Examples are mustard oil, soybean oil, sesame oil, olive oil, etc. It is good for health. It is liquid at normal temperature. Unsaturated fats are high in antioxidants. (3) & (2).


Like carbohydrates and proteins, fats are an essential part of the diet. Fat is found in nature in a variety of foods. Fat has both vegetable and animal sources.

Vegetable sources

Vegetable sources of fat include mustard oil, sunflower oil, cottonseed oil, sesame oil, almond oil, soybean oil, corn oil, bran oil, olive oil, coconut oil, etc.

Animal sources

Skim milk, cream, egg yolks, ghee, cod, and shark’s liver oil, cheese, butter, lard, suet, halibut’s liver oil, etc. are sources of animal fats.

The amount of fat depends on the source of the food.

  • First-class fat-type foods contain 100% fat. Ghee, butter, different types of oils such as nuts, mustard, cod’s liver oil, etc.
  • Second-class fat foods contain 40- 60 % fat. Examples of second-class fats are various types of nuts.
  • Third-class fat foods are low in fat. Like milk, egg, meat, fish, etc. (3) & (5).

The amount of fat is some of the sources of fats are discussed with the help of a table

Sources Amount of fat per 100 gm
1.     Lard 100
2.     Cream 19
3.     Egg yolks 27
4.     Butter 81
5.     Cheese 33
6.     Mustard oil 100
7.     Dalda 49
8.     Dark chocolate 31
9.     Avocado 15
10.  Nuts 54
11.  Beef suet 94
12.  Flaxseed 42
13.  Margarine 81
14.  Chia seeds 31

Chemical composition of fat

Lipids or fats are compounds formed by the interaction of fatty acids and glycerol. It is composed of a combination of carbon, hydrogen, and oxygen. Fat molecules have very few oxygen atoms compared to hydrogen.

Some fats contain phosphorus sulfur and nitrogen. Three molecules of fatty acids and one molecule of glycerol are joined by ester bonds to form one molecule of fats (1).

Role of fat

Fats are important biochemical substances present in the body of plants and animals. Like carbohydrates and proteins, fat also plays a significant role in the human body. The effectiveness of fat in nutrition is discussed below.

1. Energy production

Fats provide the highest energy about 9.3 kcal of energy is generated by completely oxidizing 1 gm of fat.

2. Providing a taste to the food

The presence of fat in food enhances the taste and smell of food. Thus, fat makes food delicious.

3. Hormone production

Cholesterol is a form of fat. This cholesterol further produces a hormone called testosterone and estrogen.

4. Supply fatty acids

Vegetable fats fulfill the body’s need for essential fatty acids. These types of fatty acids are needed by the human body for physical and mental development. That is why it is necessary to include 10 gm of vegetable oil in the daily diet of the human body.

5. Control body temperature

Fat is stored under the skin. The heat cannot pass through this stored fat. As a result, the body stays warm. So people who have a lot of fat in their body feel less cold than thin people.

6. Healthy skin

Fats provide essential fatty acids to protect the human body from skin diseases.

7. Supply vitamins

The fat dissolves vitamins A, D, E K in the human body, helping in their absorption and transport.

8. Other roles of fat are

  • Fat regulates the secretion of bile and pancreatic juice from the body.
  • It is stored in different parts of the body and makes the body smooth and full of beauty.
  • Fat or lipid participates in the formation of cell membranes and cell organelle in the form of phospholipid (1) & (5).

Amount of fat in the daily diet chart

People need to have a proper amount of fat in their daily diet chart. Fat provides heat and energy to the body. 20- 25% of daily energy requirement is taken from oil and fat. People need to consume 39- 40 gm of fat and oils. The amount of fats required to be included in the daily diet chart is described below.

Different age Recommendation of fats (gm/day)
1.     Babies (1 to 3 years ) 39
2.     Pre-school children (boys) 76
3.     Pre-School children (girls) 67
4.     School-age boys 86
5.     School-age girls 72
6.     Teenagers(male and female ) 50- 75
7.     Old man 45- 78
8.     Old woman 35- 60

Impact of excess fat in the human body

Fat is an organic compound that is the primary source of heat and energy in the body. The human body needs to have enough fat in its daily diet chart. But taking large amounts of fat causes various diseases. Excessive amounts of fat in the diet can cause various problems in the human body. Such as-

  • Tiredness: Excessive fat intake via food causes tiredness.
  • Indigestion: As we all know that fat is a complex component therefore large amounts of fat cause indigestion in the body.
  • Excess fat is one of the leading causes of heart disease.
  • Fat accumulates in the blood vessels and reduces the diameter of the blood vessels. The result is atherosclerosis disease.
  • Excess fat blocks the absorption of calcium in the human body.

Therefore, the amount of fat in the food needs to be kept accurate. An adult person should take 50 gm of fat in his daily diet chart. The amount of fat in the daily diet chart should be kept normal. Eating too much fat is harmful to the body as well as causes physical problems.

Fat keeps skin smooth. Therefore when the amount of fat in the body is less, it directly affects the skin. The skin becomes dry and rough. Also, the water balance in the body is disturbed, stomach diseases are seen, physical growth is reduced. Hence like carbohydrates and proteins, fats also play a vital role in the human body and nutrition (3) & (5).

Written By: Manisha Bharati


  1. Chandrasekhar Chakrabarti. Modern approach to a text book of core Zoology, General & Honours. Nirmala library, A Publishing House under the Prestigious International Standard Book Number (ISBN) System. Kolkata, (India). Part – II, chapter 25-carbohydrates, protein & lipid. Page: 2nd -25- 36 to 2nd– 25 – 46.
  2. Ajoy Paul. Zoology Honours (volume 1). Books and Allied (P) Ltd., Kolkata (India). Chapter 2: fats. Page no: 761 to 770.

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