DIET AND NUTRITION
GOOD HEALTH not only implies freedom from disease, but physical, mental and emotional fitness as well.
You may have been told that certain foods are very important for maintaining good health, while others are harmful.
(As you study the science of Foods and Nutrition, you will need to examine the ideas you have about foods very carefully and accept or reject these in the
light of the knowledge you will acquire). Whatever you learn in this area Diet and Nutrition should be used and applied in your per-
sonal life.
What do u mean by the word Diet and by the word Nutrition :
Food is that which nourishes the body. Food is anything eaten or drunk, which meets the needs for energy building, regula-
tion and protection of the body. In short, food is the raw material from which our bodies are made. Intake of the right kinds
and amounts of food can ensure good health, which may be evident in our appearance, efficiency and emotional well-being .
DIET : Diet is the kind of food which we eat. Diet refers to whatever you eat and drink each day. Thus it includes the normal
diet you consume and the diet people consume in groups (hostel diet). Diet may also be modified and used for ill persons as
part of their therapy (therapeutic diets).
NUTRITION has been defined as food at work in the body. Nutrition includes everything that happens to food from the time
it is eaten until it is used for various functions in the body. Nutrition is the result of the kinds of foods supplied to the body
and how the body uses the food supplied.
What are Nutrients: NUTRIENTS are components of food i.e, substances found in food that are needed by the body in
adequate amounts in order to grow, reproduce and lead a normal, healthy life. Nutrients include proteins, fats/lipids, carbo-
hydrates, minerals, vitamins and water.
The foods which we use daily include rice, wheat, dal, vegetables, fruits, milk, eggs, fish, meat, sugar, butter, oils, etc. These
different foods are made up of a number of chemical components called nutrients.
There are two types of Nutrients:
Some are needed in relatively larger amount are known as MACRONUTRIENTS.
Some are needed in smaller amounts called MICRONUTRIENTS.
Carbohydrates, Proteins, Fats/Lipids and water are MACRONUTRIENTS because most of the weight of the food is due to
these nutrients. They give Satisfaction value.
Vitamins and Minerals are MICRONUTRIENTS as they contribute small amount of total weight of food. 13 essential vita-
mins: Vit A,C,D,E,K,B1,B2,B3,B5,B6,B7,B9,B12, major Minerals like Ca,Chloride,Na,K,Ph Mg and Sulphur etc
There are several nutrients in each of these groups. Thus there are over 40 essential nutrients supplied by food, which are
used to produce literally thousands of substances necessary for life and physical fitness.
{The study of the science of nutrition deals with what nutrients we need, how much we need, why we need these and where we can get them.}
The excessive consumption or the deficiency of both macronutrients and micronutrients have a negative impact on the
health. Therefore it is important to have a balanced diet which includes an adequate and required quantity of both macronu-
trients and micronutrients.
Adequate, optimum and good nutrition are expressions used to indicate that the supply of the essential nutrients is correct in amount and propor-
tion. (It also implies that the utilisation of such nutrients in the body is such that the highest level of physical and mental health is maintained
throughout the life-cycle) i.e. your mental and physical health directly depends upon the adequate utilisation of these nutrients.
MALNUTRITION
Malnutrition means an undesirable kind of nutrition leading to ill-health. It results from a lack, excess or imbalance of nutri-
ents in the diet. It includes undernutrition and overnutrition. Undernutrition is a state of an insufficient supply of essential nu-
trients.like excessive carbohydrate intake causes Obesity and cardiovascular diseases. Deficiency of Vit A causes Blindness
and deficiency of Vit D causes Rickets
Malnutrition can be primarily be due to insufficient supply of one or more essential nutrients; or it can be secondary, which
means it results from an error in metabolism, interaction between nutrients or nutrients and drugs used in treatment.
Overnutrition refers to an excessive intake of one or more nutrients, which creates a stress in the bodily function.
FUNCTIONS OF FOOD: Now what does food do to your body?
1. Energy Giving The first function of the body is to provide energy ( by Carbohydrates and fats). The body needs energy to
sustain the involuntary processes essential for continuance of life, to carry out professional, household and recreational activ-
ities, to convert food ingested into usable nutrients in the body, to grow and to keep warm. The energy needed is supplied by
the oxidation of the foods consumed.
2. Body building One of the most important functions of food is building the body (by Proteins) . A newborn baby weighing
2.7-3.2 kg can grow to its potential adult size of 50–60 kg if the right kinds and amounts of food are eaten from birth to
adulthood. The food eaten each day helps to maintain the structure of the adult body, and to replace worn out cells of the
body.
3. Regulatory The third function of food is to regulate activities of the body (by Proteins,Vitamins, Minerals, Water) . It in-
cludes regulation of such varied activities as:
1) Beating of the heart
2) Maintenance of the body temperature
3) Muscle contraction
4) Control of water balance
5) Clotting of blood
6) Removal of waste products from the body
4. Protective: The fourth function is to improve our body’s resistance to disease ( by Proteins, Vitamins, Minerals).
WHAT IS METABOLISM:
Our body is made of a complex structure of cells, tissues and organs. How does this change from food to our body structure
occur? All the changes that occur in the food from the time we eat it, to its use in the body and discarding of the waste matter
are known as metabolism.
Use of Food in the Body
The use of food in the body involves three processes — digestion, absorption and utilisation of nutrients in the body.
Digestion is the process, which releases many nutrients in the forms the body can use, by breaking up food in the intestinal
tract.
Absorption is the process which carries these nutrients into the circulation system(blood) and delivers them to the cell.
Utilisation. A large number of the chemical reactions in the cell utilise the nutrients absorbed for obtaining energy and
growth and repair of the body.
Mechanical processes involved in digestion include chewing of food, swallowing of food, churning action in the stomach and rhythmic contraction of
the intestinal tract.
Chewing of food reduces the food particles in size, mixes these with saliva and dilutes it with water, so that it is easy to swal-
low. The food swallowed is mixed with enzymes and acid by the churning action in the stomach. Further the rhythmic con-
traction of the intestine, help to break the food into small particles and move the food mass forward through the digestive
tract (Figure 2.2).
ENZYMES:
Chemical reactions in digestion process: The first reaction is splitting with the help of water. Carbohydrates, fats and proteins break up
with the addition of water into smaller molecules, which the tissues can use.
The chemical reactions are accelerated by enzymes, which are secreted in the mouth, stomach and small intestine.
The digestive enzymes are only one group of a large number that are essential to regulate body processes. Other enzymes are
present in various tissues of the body and help in the utilisation of food that has been absorbed.
The digestive system breaks down the food and absorbs nutrients for energy and growth.
It is a long tube starting from your mouth, going all the way to your Anus.
The functions of nutrients are given below.
Carbohydrates: Starch found in cereals(rice, wheat, oats,Barley) and sugar in sugarcane and fruits are examples of carbohy-
drates in foods. The chief function of carbohydrates is to provide energy needed by our body. Those not used immediately
for this purpose are stored as glycogen or converted to fat and stored, to be mobilised for energy supply when needed.
Sources of Carbohydrates: Black gram,Whole grams, Whole pulses, Honey, Jaggery, Rice, Cereals, Roots(Potato), Sweet
Potato, Ripe Mango and Wheat.
Fats: Oils found in seeds, butter from milk, and lard from meat, are examples of fats found in foods. Fats are concentrated
sources of energy, carriers of fat soluble vitamins and a source of essential fatty acids. If excess fats are taken in the diet,
these are stored as fat reserves in the body. Energy taken in excess of body needs, is stored as fat in the body. Sources of
Fats: Almonds, Red meet like lamb, beef and pork, Chicken and other poultry,Milk ,Dairy products, Cheese and Ice cream,
Butter,Eggs, Palm and Coconut oils.
Proteins: Casein from milk, albumin in egg, globulins in legumes(lentils, peas, Chickpeas, soyabeans) and gluten in wheat,
are examples of proteins occurring in foods. The main function of protein is the building of new tissues and maintaining and
repair of those already built. (Synthesis of regulatory and protective substances such as enzymes, hormones and antibodies is also a function
of food proteins). About 10 per cent of the total energy is supplied by proteins in the diet. Protein, when taken in excess of the
body’s need, is converted to carbohydrates and fats and is stored in the body. Sources of Proteins: Goat meat, Fish, Eggs,
Milk(cow), Soyabean, Cottage cheese, Groundnuts.
Minerals: The minerals calcium, phosphorus, iron, iodine, sodium, potassium and others are found in various foods in com-
bination with organic and inorganic compounds. Minerals are necessary for body-building, for building of bones, teeth and
structural parts of soft tissues. They also play a role in regulation of processes in the body, e.g., muscle contraction, clotting
of blood, nerve stimuli, etc. Sources of Minerals: Nuts and seeds, Vegetables,Shellfish, Liver, Red meat,Green leafy vegeta-
bles, fish etc
Vitamins: Fat-soluble vitamins A, D, E and K and also water-soluble vitamins C and B group are found in foods. These are
needed for growth, normal function of the body and normal body processes. Sources of Vitamins: Citrus fruits, red and green
peppers, Strawberries, blueberries, blackberries, green leafy veggies like Broccoli and sprouts, potatoes ,Fish, Mushrooms,
Nuts, Seeds.
Water: We get water in foods we eat and a major part from the water we drink as such and as beverages. Water is an essen-
tial part of our body structure and it accounts for about 60 per cent of our body weight. Water is essential for the utilisation of
food material in the body and also for elimination of food waste. It is a regulator of body processes such as maintenance of
body temperature.
Sources of water: Melons like watermelon, honeydew, strawberries, Bell peppers, Peaches, Oranges, celery basically fruits
have lots of water content in them
All individuals need the same nutrients for the same body function. The only variation is in the amounts of each nutrient re-
quired according to age, size, activity, etc. For example, all persons need energy for work, but a man, who carries loads may
need more energy than a man, who works in an office at a desk job.
As you know, we get the nutrients from the foods and the beverages we consume. Most foods contain the nutrients in varying
amounts. Let us understand the nutrient composition of the foods we use everyday.
Diet and Heart Ailments
Fat is essential for our health, but too much of it can lead to ill health. We have a high intake of fat, a large part of it is satu-
rated fats (milk sweets, eggs and other flesh foods), and a very sedentary lifestyle. Their energy intake in excess of needs
leads to obesity and an unacceptable blood lipid profile. If unchecked, there is deposition of fatty material with formation of
plaques in the arteries, which disturbs the movement of oxygen and nutrients. It leads to a variety of heart ailments, such as
atherosclerosis, high blood pressure and others.
There are a number of factors associated with susceptibility to heart ailments that can be controlled to a great extent. These
include elevation of plasma lipid levels, obesity, physical inactivity and heavy smoking.
What is Energy?
[Energy is the capacity to do work. Energy exists in a number of forms. It may occur as heat generated by chemical, mechanical or electrical means.
Examples are:
1. Heat produced by chemical means, e.g., when lime and water are mixed.
2. Heat produced mechanically in the grinding stone when cereals are ground.
3. Heat generated by electric current for boiling water in a tea kettle. ]
One form of energy can be converted to another form.
In physiology and nutrition, energy is defined as the capacity of a body to do work. Just as a machine needs fuel to keep it
operating, the body needs food to provide the energy to perform its various tasks.
The energy released in the body from food is measured as a unit of heat the kilocalorie (kcal). By definition, one kilocalorie
is the amount of heat required to raise the temperature of one kilogramme of water through one degree centigrade (i.e., from
14.5° to 15.5.°C).
The machine which measures the energy value of foods is Bomb Calorimeter.
Calorie value of various types of food:
1gm of carbohydrate produces 4 kcal energy
1gm of protein produces 4 kcal energy
1 gm of Fat produces 9kcal energy
Another unit of energy is kilojoules.
It must be remembered that the human body uses energy in many forms hence the unit used in measurement is only an indi-
rect indication of the energy available to the body in various forms (chemical, thermal, mechanical, electrical, etc.).
Food supplies the energy we need for everything we do. Two components of food, carbohydrates and fats, supply 85 to 92
per cent of the total energy in the Indian dietary, the rest is provided by proteins.
Calories per 100
Food Moisture % Fat %
g
Cucumber 96 0.1 13
Tomato 94 0.2 20
French beans 91 0.1 26
Orange, Carrot 88 0.2 48
Milk, cow’s 87 4.1 67
Grapes 79 0.3 71
Potato 75 0.1 97
Egg 73 13.3 173
Mutton, muscle 71 13.3 194
Wheat 13 1.5 346
Groundnut (Peanuts) 3 40.1 567
Butter 19 81.0 729
Oil, Ghee or Vanaspati 0 100.0 900
Energy Intake
The main source of energy for all the body activities is food, along with the energy store in body tissues as reserve.
Our body needs fuel to carry out its work on a continual basis. This need starts at birth and continues as long as one lives.
The metabolic products formed by digestion of carbohydrates and fats, which are simple sugars, glycerol and fatty acids, pro-
vide most of the energy needs of the body. One can summarise the energy production from foods as:
Glucose, fatty acids, glycerol or amino acids + oxygen ® ® energy + carbon dioxide + water
The energy released is trapped in energy-rich compounds (ATP), from which it is released as required.
While we may eat two, three or four meals a day, which supply energy to the body at intervals, our body activities (voluntary
and involuntary) go on throughout the day, even while we sleep. The body draws on its stores of energy to meet its continu-
ous need for energy.
Light work people need 2200-2500 kcal per day
For moderate work, individual needs 2500-2900 kcal per day
For heavy work (like rickshaw pullers) individual need 2900-3500 kcal per day
Sex Activity Body weight (kg) Energy (kcal)
Sedentary 60 2425
Man Moderate 60 2875
Heavy 60 3800
Sedentary 50 1875
Woman Moderate 50 2225
Heavy 50 2925
Table 7.6: Energy Requirement of Reference Individual
1950 Calories 2225 Calories 2875 Calories 2225 Calories
Figure 7.1: Energy needs vary with activity.
Effects of Insufficient Energy Supply
The effects of insufficient energy supply vary with the age group affected and the extent of insufficiency. In adults, it may af-
fect their capacity for work, in children it affects their growth and activity. If the energy supply is very short of what is
needed, the body stores of fat may be used, followed by use of the muscle tissues to meet the need for minimal function of
the body.
WHAT IS METABOLISM:
Our body is made of a complex structure of cells, tissues and organs. How does this change from food to our body structure
occur? All the changes that occur in the food from the time we eat it,(i.e. the chemical processes going on continuously inside the
body) to its use in the body and discarding of the waste matter are known as metabolism.
Basically the amount of energy that our body burns at any given time is affected by our metabolism.
UTILISATION OF ENERGY :
There are 3 ways by which the energy is utilised or consumed.
1) BMR : BASAL METABOLIC RATE :Even at rest, the body needs energy to keep all systems functioning correctly
(such as breathing, keeping the heart beating to circulate blood, growing and repairing cells and adjusting hormone lev-
els). The body’s BMR accounts for the largest amount of energy expended daily (50-80% of our daily energy use).
As your BMR accounts for so much of your total energy consumption, it is important to preserve or even increase your
lean muscle mass through exercise when trying to reduce weight. An average man has BMR of 7100kJ per day, average
woman has average BMR of around 5900kJ per day.
2) Physical activity :
3) Specific dynamic action (SDA)
Maintenance of Body Weight
Weight is one of the gross parameters of our health. It is advisable for a person to maintain that weight throughout life. This
is the reason why all tables indicate desirable weight for height for men and women at 25 years (Tables 7.8 and 7.9).
When energy intake is equal to body needs, body weight is maintained at a fairly constant level, in a healthy adult. Thus con-
stant body weight is an index of energy balance in healthy adults.
Consistent intake of inadequate food, which is unable to meet the body’s need for energy, leads to use of body fat to make up
the deficit and there is loss of weight. An underweight person has reduced capacity for work, vitality and decreased resis-
tance to disease.
On the contrary, continuous intake of energy in excess of one’s needs, results in deposition of fat. Overweight is associated
with ailments of heart, circulatory system, kidneys and diabetes.
Table 7.8: Males (25 yrs.) Weight for Height for Males and Overweight-Underweight Limits
Height (cm) Weights1.2 (kg) Overweight limit3 (kg) (+20%) Underweight limit3 (kg) (–20%)
148 47.5 57.0 38.0
152 49.0 59.0 39.0
156 51.5 62.0 41.0
160 53.5 64.0 43.0
164 56.0 67.0 45.0
168 59.0 71.0 47.0
172 62.0 74.5 49.5
176 65.5 78.5 52.4
180 68.5 82.0 55.0
184 72.0 86.5 57.5
188 75.5 90.5 60.5
190 77.5 93.0 62.0
Table 7.9: Females (25 yrs.) Weight for Height and Overweight-Underweight Limits
Height (cm) Weights1.2 (kg) Overweight limit3 (kg) (+20%) Underweight limit3 (kg) (–20%)
148 46.5 56.0 37.0
152 48.5 58.0 39.0
156 50.5 60.5 40.5
160 52.5 63.0 42.0
164 55.0 66.0 44.0
168 58.0 69.5 46.5
172 60.5 72.5 48.5
176 64.0 77.0 51.0
180 67.0 80.5 53.5
184 70.5 84.5 56.5
188 74.0 89.0 59.0
BALANCED DIET
Is a diet that contains an adequate quantity of the nutrients that we require in a day. A bal-
anced diet includes 6 main nutrients. A well balanced diet lowers the risk of disease and en-
hances general health. So meal planning should be done according to the conditions like he is
a old man or young, man or woman, sedentary, moderate or heavy work group. This will help
determine the kind of nutrition the individual needs. e.g. during adulthood nutrients are re-
quired basically for maintenance of body functions, therefore their diet should include suffi-
cient amount of all three categories : Energy giving, body building, protective and
regulatory ,all.
Food Selection: The amounts of foods included from the various groups will depend on the body size and activity of the in-
dividual. Thus a labourer, who is very active may need more cereals and oils and fat to meet his/her energy needs as com-
pared to a sedentary person, who is involved in desk work. The foods selected need to be used in the day’s meals, which fit
into the daily schedule of the person.
Nutritional assessment is used to decide the nutritional status of the patient.
Body Mass Index (BMI), a value calculated from height-weight data, is an indicator of the body fat content. Standards of
BMI have been developed for use in judging the health status of the person. (Table 24.1)
BMI = Wt. in kg / Ht. in metre2
Table 24.1 BMI in Adults (Men and Women)
Adults BMI
Normal 19-24
Obesity – Grade I 25-29
Obesity – Grade II 30-40
Obesity – Grade
>40
III
Table 16.1: Food Plan for a Day.
The daily food plan Sample menu
Milk (2 servings) Breakfast
Dal (2 servings) Upma, milk, banana, tea
Vegetables (3 servings)
Fruit (1 serving) Lunch
Cereals (10 servings) Rice, chapati, dal, vegetable beans, carrot and cabbage
mixed salad, dahi/lassi
Sugar
Oil, fat
Tea
Breakfast
Tea, bread and butter
Cereal and milk, fruit
Lunch
Dinner
Cereals, dal, two vegetables, dahi
Rice, roti, dal, leafy vegetables, dahi
Dinner
Cereals, dal, leafy vegetables, dahi.
How will you be a responsible nutrition student?
First, use what you learn in nutrition and benefit yourself. It will help you to look better, feel better and work effectively. By
practising what you learn, you will set a good example for others.
Secondly take care of nutrition of your family. Help the children in the family to develop good food habits, the adults to
make good food choices in eating and seniors to meet their changed needs. Thirdly, as a professional you will be able to help
people, who seek your advice, to make appropriate
changes to improve their food choices to improve their well-being.
Lastly, as a member of the community, you can influence the choice of foods served in social
events.
