Sports and Nutrition Revision notes Class 12 Chapter 2 Physical education
Balanced Diet and Nutrition
A Balanced diet can be defined as ‘A diet which consists of all the essential food constituents, viz., proteins, carbohydrates, fats, vitamins, minerals and water in correct proportion. In other words, it means eating the right amount of food from all food groups which provides all essential food constituents necessary for growth and maintenance of the body.
Nutrition can be defined as the science of food and its relationship with health. It includes a dynamic processin which the food consumed is digested, nutrients are absorbed and distributed to the tissues for utilisation and wastes are disposed of the body. Nutrients are the chemicals derived from the food consumed and used by the body for proper functioning.
There are two kinds of nutrients that we consume in the form of food. They are discussed below:
(1) Macro Nutrients
These constitute the majority of an individual’s diet and thus can be taken in large amounts. They supply energy and aid growth and maintenance of the body.
The various macro- nutrients are discussed below:
» Carbohydrates
Carbohydrates are the main source of energy made up of carbon, hydrogen and oxygen in 1:2:1 ratio. Carbohydrates are organic compounds which are important for our digestive process. They are required by the body for performing every day tasks. But,excess of carbohydrates increases weight.
There are two main types of carbohydrates.
● Simple Carbohydrates: They are sweet, crystalline and soluble in water. They form sugar—glucose, fructose, galactose, sucrose, maltose and lactose.
● Complex Carbohydrates: They are non- sweet, non- crystalline and insoluble in water. They include starch, dextrine, glycogen and cellulose.
» Proteins
Protein is a large compound formed of carbon, hydrogen, oxygen, nitrogen and sulphur. As they form a large molecules, proteins are converted into amino acids by our digestive system. These amino acids are used by the body for creation of blood, muscles, nails,skin, hair and tissues in internal organs. They also form new tissues, repair broken tissues, regulate balance of water and acids, transport oxygen and nutrients and make antibodies.
Our body requires only 0.36 grams of protein per pound of body weight. Excess of protein in body can lead to heart disease, osteoporosis, stroke and kidney disease, while its deficiency can cause Marasmus and Kwashiorkor. Rich sources of proteins are egg, dairy products, pulses, nuts, and food grains.
» Fats
Fats are compounds made up of 76% carbon, 12%
oxygen and 12% hydrogen. They function to keep
us warm, protects our organs and aid the
production of hormones. They also regulate body
temperature.
Foods rich in fats are butter, oil, sausage, cheese,
fish, chocolate, olives and nuts.
(2) Micro Nutrients
Micro nutrients are extremely significant in proper
functioning of the body. They function to enable
chemical reactions in the body and are required in
small amounts. They are discussed below:
» Vitamins
Vitamins are compounds of carbon which are
essential for the normal growth and working of the
body. There are compored of carbon, hydrogen and
oxygen and they are two groups of vitamins i.e. fat
soluble and water soluble :
1. Fat Soluble Vitamins These vitamins are
composed of carbon, hydrogen and oxygen and
they are easily dissolved in fats.
The fat soluble vitamins are
(i) Vitamin A It was the first vitamin discovered
by Elmer McCollum in 1913. It is an
essential nutrient helpful in the normal growth
of the body and development of eyes and
skin. Its deficiency can cause Night
blindness and can have severe impact on
skin, teeth, kidneys, nervous system and
digestive system. Its rich sources are egg
yolk, milk and milk products, mango,
papaya, etc.
(ii) Vitamin D This white colourless crystalline
vitamin is essential for the formation of
healthy teeth and bones. The presence of
this vitamin in the body enables the body to
absorb calcium and phosphorus. Deficiency
of this vitamin can cause rickets, dental
cavities and osteoporosis. Its rich sources
are milk, butter, sunrays and fish liver oils.
(iii) Vitamin E This vitamin essentially maintains
the functioning of reproductive organs. It also
helps in blood coagulation, strengthening the
cell membrance and keeping the skin
healthy. Its deficiency can cause
degeneration of muscles, paralysis and slow
growth. Its rich sources are green leafy
vegetables, sprouts, egg and whole cereals.
(iv) Vitamin K Its mains function is to clot blood
to prevent excessive bleeding or
haemorrhage. Its deficiency can cause
anemia. Its rich sources are cauliflower,
spinach, cabbage, tomato, potato, wheat, etc.
2. Water Soluble Vitamins These vitamins are soluble in
water. They are
(i) Vitamin B Complex This vitamin consists of 8
vitamins. They are mentioned in the table.
4. Magnesium (Mg) It repairs and maintains body
cells. It’s sources are meat, brown rice, beans,
whole grains etc.
5. Phosphorus (P) It is required for development of
strong bones and teeth and keeps muscles and
nerve activities normal. It is found in egg, fish,
meat, milk etc.
Micro Minerals
Some of the micro minerals are as follows :
1. Iodine (I) It is essential for the production of
hormone in the thyroid gland. Its deficiency can
hinder growth and development. It can cause
dwarfism, rough and fatty skin and goitre. Its rich
sources are iodised salt, fish and sea food.
2. Iron (Fe) It is important for the formation of
haemoglobin. Its deficiency can cause anemia. Its
rich sources are meat, egg, dry fruits, spinach,
banana and green leafy vegetables.
3. Chromium (Cr) It stimulates insulin activity. Its
deficiency can cause diabetes. Its rich sources are
carrot, tomato, bajra, barley and soyabean.
4. Copper (Cu) It is helpful in the formation of red
blood cells, connective tissue and nerve fibre
formation and functioning. Its rich sources are
eggs, pulses and green leafy vegetables.
5. Cobalt (Co) Cobalt is needed for making
red blood cells. It protects us from anemia and
is found in green leafy vegetables, milk and
meat.
6. Fluorine (F) It is important to make the enamel
(polish) of the teeth hard and prevents dental
diseases.
Nutritive Components of Diet
Nutritive components of diet are those components
which contribute or provide energy or calories. The
nutritive components of diet are proteins,
carbohydrates, fats, vitamins and minerals.
Non-nutritive Components of Diet
Non-nutritive components of diet do not provide
energy or calories. Their main purpose is to make the
food smell and taste better, last longer, or look better
etc.
Some of the important non-nutritive food components
are discussed below
1. Roughage or Fibre It is the undigested part of the
food which functions to satisfy the appetite. It is
essential as it increases the function of intestinal
tract and prevents constipation.
2. Water It is non-nutritive but essential component
of diet. It acts as a lubricant for the various body
parts such as skin.
3. Plant Compounds These are derived from plants
and can include both nutritive and non-nutritive
compounds. Its non-nutritive elements can pose
several health risks.
4. Colour Compounds Colours are added to the food
to make it look attractive and colourful. These are
derived from animal products, grains as well as
fruits and vegetables.
5. Flavour Compounds These are flavouring agents
that add flavour to the food.
6. Food Addictives Certain chemicals like benzoic
acid, sodium benzoate and other chemicals are
used as food preservatives to increase the shelf life
of the food.
Eating for Weight Control
» Eating the right amount will lead to healthy weight.
» Eating too much can lead to obesity and too less can
lead to underweight.
» An individual who has a healthy weight leads a healthy
life with reduced risk of diseases.
» A Healthy Weight
» A healthy weight refers to an ideal body weight at which
there is a reduced risk of diseases such as heart
diseases, high blood pressure, diabetes, etc.
» For optimum health, body fat should not be more than
20% of total weight for men and 30% for women. Healthy
weight can be measured through calculating BMI.
Body Mass Index (BMI)
BMI method is used to check if an individual has an
ideal weight with respect to his/her height. According to
the BMI score, individuals are categorised into
underweight, normal weight, over weight and obese.
The data differs for both men and women.
To calculate BMI, take the weight in kilograms and
divide it by square of height taken in metres. i.e.
BMI =
Body weight in kg
(Height in metres)2
The Pitfalls of Dieting
People use various techniques of weight loss such as
taking diet pills, fasting, reducing calories consumption,
exercise, etc. There are some dangers /pitfalls of dieting
that need to be checked for reducing weight in a healthy
way.
The pitfalls of dieting are
(i) Eating too little
(ii) More Drinking than Eating
(iii) Skipping meals
(iv) Intake of Labelled Foods
(v) Not Performing Exercises
Food Intolerance
Food intolerance is the intolerance of certain elements
in some foods that cannot be properly processed by
our digestive system. Features of food intolerance are
as follows
● Usually comes on gradually.
● May only happen when you eat a lot of a
particular food.
● Causes of Food Intolerance It is caused by part
or complete absence of activity of the enzymes
responsible for breaking down or absorbing the
food elements. Some intolerance can be
diet-related or due to illness.
● Symptoms of Food Intolerance It can cause
nausea, stomach pain, diarrhoea, vomiting, gas,
cramps, heartburn, irritability, nervousness, etc.
● Management of Food Intolerance It includes
dietary changes with or without professional help.
If one is unaware about the food causing the
problem, a general medical practitioner would
assist in diagnosis and management.
Foods Myths
Various food myths prevail in India and the world.
People believe in these myths because the myths
seem credible. However, now that we have advanced
scientific knowledge, we can dispel these myths. The
most common food related myths are
● Potatoes make us fat.
● Fat-free products help in reducing weight.
● Eggs increase the cholesterol level.
● Drinking water while eating makes us fat.
● Don’t consume milk immediately after
eating fish.
● Starve yourself if you want to lose weight.
● Exercising makes you eat more.
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