The document discusses key concepts in dietetics and nutrition including calories, basal metabolic rate, specific dynamic action, and physical activity. It defines important terms like calorie, kilocalorie, basal metabolic rate, specific dynamic action or thermic effect of food. It explains that calories come from carbohydrates, fats and proteins and provides the caloric values of each. Basal metabolic rate accounts for 60-75% of daily energy expenditure and is influenced by factors like body composition, age, and thyroid function. Physical activity and specific dynamic action account for the remaining calories burned.

1. BBy
Dr.Geeta Jaiswal

2. The Study of Dietetics
 A sound knowledge of the
principles of nutrition is of
paramount importance in all
developing countries where
more than 60 % of the
population is under the poverty
line

3. Dietetics is a science of Food
and Nutrients
The action and interaction of
nutrients, their balance as well
as imbalance in health and
disease

4. Calorie is :- the energy content of food
materials
 We count them.
 We trim them.
 We fret over them.
 We work hard at burning them off, but we
can’t even see them.
 Calories are simply a unit of energy, but
they are a great mystery to many.
 They are not the enemy dieters often think
they are.

5. How is a Calorie defined
 1 calorie is the heat required to raise the
temperature of 1 g of water through 1⁰c.
 To a scientist, a calorie is the quantity of heat
(or energy) needed to boost the temperature of
1 ml of water by 1˚C
 A kilocalorie (kcal, often pronounced kay-cal)
is the amount of heat required to raise the
temperature of 1000 ml of water by 1˚C.
One kilo calorie = 4.2 kilo joules

6. A kilocalorie is = 1000 calories.
Even though there is 1000-fold
difference between these two
values
 Calorie and kilocalorie are
often used synonymously when
discussing food and eating

7. Calorie and kilocalorie will not be used to
mean the same thing in this text.
 When you see food
labels say that a
serving of food is
100 calories, the
real meaning is
that the food has
100 kcals.
 Likewise, when we
say that running a
race burned 300
calories, we mean
300 kcals.

8. We need calories from food and drink
to run our bodies the same way a car
needs energy from gasoline and your
refrigerator needs electric energy to
keep your food cold.
The main purpose of food is to provide
energy for various muscular activities
And also to supply the basic body
building materials such as essential
amino acids and fatty acids

9. Calorific Value or Energy Density
The calorific value of nutrients is also
known as “Energy density” = energy yield
per unit weight of food
Calorific Value of Nutrients
Nutrient Energy yield
kcal / g
Energy yield
k j/ g
Carbohydrate 4 16
Fats 9 37
Proteins 4.2 17
Alcohol 7 29

10. Your body weight reflects your energy balance.
 If you consume more
calories than your body
uses, you will gain weight.
 Likewise, you will lose
weight if you consume fewer
calories.
 Body weight is not,
however, an indicator of
nutrient adequacy or the
nutritional quality of the
diet.

11. There are three components to your
metabolic rate:
Physical activity,
 Resting metabolic rate
(BMR)
The thermic effect of food.
(SDA)

12. Physical Activity
Physical activity - whether is it
purposeful exercise such as jogging,
activities of daily living such as
typing and folding laundry, or
simply unconscious fidgeting - is
the only component of the three
that you have much control over.

13. Resting Metabolic Rate (RMR)
The greatest component is
the resting metabolic rate
(RMR). It is responsible for
60–75 per cent of the total
calories burned each day.

14. Thermic Effect of Food
The digestion, absorption and
storage of food is called the
thermic effect of food (TEF) –
It is the smallest component.
Let’s take a closer look at each of
these components.

15. Resting Metabolic Rate (RMR) and
Resting Energy Expenditure (REE)
You burn calories all day and night
even if you do nothing but sleep or
watch TV.
Most of the calories spent each day are
for breathing, circulation, maintaining
your body temperature, moving
compounds in and out of cells, and
other normal body processes you rarely
need to think about.

16. REE – Determinants
Are as follows

17. 1.Body Mass :Lean body mass (LBM)
• This is the greatest determinant of REE.
• It includes water, bone, skeletal muscles,
and other organs such as the liver, brain and
heart. These organs drive most of the REE.
• For example, the liver accounts for
approximately 29 per cent of your REE.
• Skeletal muscle at rest is a smaller portion
of your REE, accounting for approximately
18 per cent.

18. • Building muscle will then increase
your metabolic rate, but it is not
the metabolic furnace many
people believe it to be.
• To make a large difference in REE,
an individual would need to gain
quite a lot of skeletal muscle.

19. • More calories are likely burned
in building and maintaining the
muscle than from the muscle’s
effect on the REE.
• In fact, the resting metabolic
rate of athletes is only about 5
per cent greater than non-
athletes.

20. 2.Body size. Generally, the greater the
body’s surface area, the greater the
metabolic rate.
3.Age. The REE is greatest during
periods of growth such as infancy,
toddlerhood and adolescence.
REE declines two to three per cent per
decade after early adulthood. The typical
loss of LBM with aging does not account
for the full drop in energy expenditure.

21. 4.Gender.
At the same age and weight, men usually have a
higher REE because of the difference in body
composition. Men usually carry more muscle
than women.
5.Other factors.
A women’s menstrual cycle will increase her
REE, explaining, in part, the dreaded weight
creep that often comes with menopause.
Having a fever or being in extreme
temperatures also increases the REE.

23. BASAL METABOLIC RATE
The basal metabolic rate
(BMR) is the energy
required by an awake
individual during physical,
emotional & digestive rest.

24.  It is the minimum amount
of energy required to
maintain life or sustain vital
functions like the working of
the heart, circulation, brain
function, respiration, etc.
 The metabolic rate during
sleep is less than BMR.

25. FACTORS AFFECTING BMR
Age-During the period of active growth,
BMR is high. It reaches a maximum by
5years of age. In old age BMR is lowered.
SEX- Males have a higher BMR than
females
Temperature: BMR increases in cold
climate as a compensatory mechanism to
maintain body temperature.
Eskimos have a higher BMR.

26. Exercise: The increase in BMR during exercise is
due to increased cardiac output. Starvation
lowers BMR
Fever: 12% increase in BMR is noticed per
degree centigrade rise in temperature.
Thyroid hormones:
Since thyroid hormones have a general stimulant
effect on rate of metabolism & heat production BMR
is raised in hyperthyroidism & lowered in
hypothyroidism.

27. The Basal Metabolic Rate (BMR)
Is the amount of energy needed to
sustain metabolic activities while an
individual is lying down and mentally
resting in a temperature-controlled
environment that prevents shivering
or sweating.
The individual should not have eaten
or exercised for at least 12 hours.

28. Since these conditions are difficult to
meet, so scientists and practitioners
typically measure the RMR instead.
The RMR is frequently measured
three or four hours after eating or
exercising and with other less strict
criteria.
 For these reasons, the RMR is higher
(3 %) than the BMR.

29. Measurement of BMR – by Atwater
Benedict Roth closed circuit method
The person whose BMR has to be
measured should be awake and in a
stage of complete physical and mental
rest
The Temperature of the surrounding
should be comfortable ( about 25o C )
The subject breathes in Oxygen from
a metal cylinder .

30. The CO2 produced is absorbed in Soda
lime
The subject is asked to breathe
through the mouth piece for 6 minutes.
The Oxygen present in the cylinder is
utilized during this time and the
volume of oxygen consumed is
recorded.

31. Calculation of BMR
BMR is calculated from
 Oxygen consumption
Calorific value and
 Surface area

32. A) Let Oxygen consumption in
6 minutes is Y Litre
B) Calorific value of 1 Litre oxygen
is 4.8
Which means
When 1 Litre oxygen is utilised
4.8 kilocalories are generated

33.  Therefore when Y Litres oxygen is utilized in 6
minutes
Heat produced will be = 4.8 x Y
 Heat produced in 60 minute
( or 1 hr) = 4.8 x Y x 10
 Heat produced in 24 hrs
= 4.8 Y x 10 x 24 K Cals

34. Indirect Calorimetry- Double labelled water
method of – Nathan and Lifson
 In this method deuterium (2H ) and 16 O labelled
water are given
 These Isotopes are eliminated at different rates
 Deuterium is eliminated as water while oxygen as
CO2
 This provides a measure of total CO2 over 2-3
weeks
 This method is used to measure alterations in
energy requirements during growth, pregnancy
and lactation

35. Normal Value for BMR
 Since BMR is affected by body surface area, it is
usually expressed in kilocalories per hour / square
meter of body surface .
 Body surface area is calculated using the formula
of Eugene Du Bois & Delafield Du Bois
 A = W x H x 71.84
 A= area in sq cm
 W= weight in Kg
 H = height in cms

36. For adult men the normal value of BMR
is 34 – 37 kcals /m2 / hour
For women , 30 – 35 kcal / m2/hour
For easier calculations BMR for an
adult is fixed at 24 kcal / kg body wt /
hour

37. SPECIFIC DYNAMIC ACTION
SDA
Thermo genic Effect of
Food

38. SDA This refers to the
increased heat production or
increased metabolic rate
following the intake of food
referred to as the Thermo
genic effect of food (diet
induced thermo genesis).

39.  Part of this is due to the expenditure of
energy for digestion; absorption & active
transport of products of the digestion.
 Another reason for this expenditure of
energy is that reserve materials such as
glycogen, triacylglycerol, protein, etc. are
synthesized from small molecules
available after digestion.

40. This energy is trapped from
previously available energy, so that
the actual energy from the food is
lesser than that of theoretical
calculation.
SDA can be considered as the
activation energy needed for a
chemical reaction. This activation
energy is to be supplied initially.

41. • Suppose a person takes food
worth = 1000kcal.
• But before this energy is
trapped about 10% energy
(=100kcal) is drawn from the
reserves of the body.
• Thus the net generation of
energy is only 1000-
100=900kcal

42. If the person wants to get
1000kcal,
He should take food worth
1100 kcal.
Thus additional calories,
equivalent to SDA have to
be added in diet

43. The values of SDA are :
For Proteins ---------- 30 %
For lipids ---------- 15%,
For Carbohydrates --- 5% .
This means that out of every 100g of
proteins consumed, the energy available
for doing useful work is 30% less than the
calculated value.

44. Hence for a mixed diet, an extra 10%
calories should be provided to account
for the loss of energy as SDA.
It is a common experience that during
hot weather following the consumption
of a protein rich meal, one feels hot &
humid for a while.
On the other hand, in cold weather, the
same would provide a comfortable
feeling .

45. Thermic Effect of Food (TEF).
 It takes energy to process the food you eat.
Digestion of the food and the absorption,
metabolism and storage of the nutrients account
for approximately 10 per cent of your total energy
expenditure.
 The composition of your meal determines its TEF
.
 Large meals have a greater TEF than small meals,
and protein has a greater TEF than carbohydrate,
which have a greater TEF than fat.

46.  In other words, eating protein “wastes”
more calories than eating carbohydrate or
fat.
Thus, by increasing the protein content or
your meal without increasing its calorie
content, you can burn a few extra calories.
The effect is not large, however. It has been
estimated that by manipulating the
macronutrient content of the diet,
someone consuming 2000 kcals per day
could burn approximately an additional 23
kcals daily.

47. PHYSICAL ACTIVITY

48. Physical Activity.
 This is the most variable
component of your daily energy
expenditure.
 For most people, it accounts for
approximately one-quarter of
their total energy expenditure.
 It may be as little as 10 per cent,
however, in someone extremely
inactive or bedridden and as
much as 50 per cent in athletes
or heavy labourers.

49.  Unlike your RMR, which is proportional to
your LBM, the calories you burn in exercise
are based on your body weight.
 For example, if a 100-pound person and a 200-
pound person took a walk at the same speed
and covered the same distance, the heavier
person would use twice as many calories as his
lighter walking companion.
 Sports specialists and researchers estimate the
calorie cost of exercise in metabolic
equivalents (MET).

50. Metabolic Equivalents
 The metabolic cost of sitting quietly is 1.0
MET and is approximately 1 kcal/kg/hr.
 Using this value, other physical activities are
assigned MET levels according to their
intensity.
 Thus, energy expended by physical activity
can be expressed in multiples of 1 MET.
 For example, walking on level ground at 3.0
mph has a MET value of 3.3, meaning it
burns 3.3 times the energy of sitting quietly.

51. The Energy Cost of Physical Activities
 As you’ll see from the list below, different
types of physical activities have different
energy costs.
 For example, a person weighing 140 pounds
(63.6 kg) burns approximately 63.6 kcals
each hour she sits quietly.
 If she walks 3.0 mph on level ground (which
has a MET value of 3.3) for one hour, she will
burn approximately 210 kcals (63.6 x 3.3).

52. Activity and METs
Sitting quietly: 1.0
Bowling: 3.0
House cleaning, general: 3.0
Walking 3 miles per hour (20-
minute mile): 3.3
Water aerobics: 4.0

53. Thank
You