The document discusses factors that affect energy requirements and methods for measuring energy expenditure. It provides details on ICMR recommendations for energy intake in India based on reference men and women. The key points are: 1. Basal metabolic rate, age, gender, body weight, occupation, climate, lifestyle, and health influence energy requirements. ICMR defines reference individuals to estimate average energy needs. 2. Methods to measure energy expenditure include direct calorimetry, indirect calorimetry using whole-body chambers or Douglas bags, stable isotope methods, heart rate monitoring, and recording time and motion. 3. Calculations of energy requirements factor in basal metabolic rate, specific dynamic action of food, and

1. MACRO NUTRIENTS
ENERGY CALCULATIONS &ICMR REQUIREMENTS
FACTORS EFFECTING ENERGY REQUIREMENTS
BY
G.RANJANI
I-M.Sc., FOODS AND NUTRITION

2. ENERGY
INTRODUCTION:
 Human beings require enough energy to lead an active and healthy life. Energy fulfils the
following functions.
 Maintenance of basal body functions
 Physical activity
 Growth and development in infants.
 The main source of dietary energy are the carbohydrates, fats and proteins. These sources of
energy , on complete metabolism, yield different amounts of energy as
ENERGY SOURCE GROSS ENERGY Kcal METABOLIZABLE ENERGY
Kcal/g
CARBOHYDRATE 4.18 4.0
FATS 9.46 9.0
PROTEIN 5.67 4.0
ALCOHOL 7.10 7.0

3.  The actual amount of metabolizable energy available is however somewhat less(90%-95%) .
Alcohol is also an important source of energy.
 An adequate and constant amount of energy must be make available to the body or cell survival
and maintaining the vital functions at optimal levels.
 carbohydrates and fats Co2 + water+ heat
 Proteins Co2+water+urea
ENERGY UNITS:
 One kilogram calorie is used to express the energy value of foods.
MEASUREMENT OF ENERGY EXPENDITURE:
 The ability to measure human energy expenditure has been important in many aspects of
nutritional science.

4. METHOD MEASUREMENT
PRINCIPLE
ADVANTAGES APPLICATIONS
 DIRECT
CALORIMETRY
WHOLE-BODY
CHAMBER
 Subject confined within a
small to moderately sized
chamber
 Measures heat loss
 Historically had
faster response time
than indirect
calorimetry.
 Good environmental
for strictly
controlled studies
 Initially used to
validate the
principle of indirect
calorimetry.
 Some distinct
applications in
studying heat
dynamics of exercise
 Now largely
obsolescent.
BODY SUIT  Subject wears an insulate
metabolic suit
 Historically had
faster response time
than indirect
calorimetry.
 Good environmental
for strictly
controlled studies
 Initially used to
validate the
principle of indirect
calorimetry.
 Some distinct
applications in
studying heat
dynamics of exercise
 Now largely
obsolescent.

5. METHOD MEASUREMENT
PRINCIPLE
ADVANTAGES APPLICATIONS
 INDIRECT
CALORIMETRY
WHOLE BODY
CHAMBER
 Subject confined within a
small to moderately sized
chamber
 Measures oxygen
consumption and
frequently also measures
co2 production
 Calculates EE from
energy equivalence of
oxygen consumed
 Calculates
macronutrient oxidation
from RQ after
adjustment for urinary
nitrogen losses
 Very precise and
repeatable
 Provides minute by
minute data
 Measurements over 1-
14 days
 Good environment for
strictly controlled
studies
 Measures
macronutrient
oxidation rates in
addition to total EE
 Represents gold
standard
 Fundamental studies
of the mechanisms
regulating human
energy balance
 Includes effect of
exercise, diet
physiological states
such as pregnancy
and pharmacological
effects of compounds
intended to affect
energy expenditure

6. METHOD MEASUREMENT
PRINCIPLE
ADVANTAGES APPLICATIONS
DOUGLAS BAG METHOD  Subject wears mouthpiece
with one way valve and
nose clip
 Collect expired air directly
into an impermeable
“Douglas” bag then
measures volume and gas
 Concentration of Bag
contents
 Calculation as for whole
body indirect calorimetry
 Simple and robust
 Provides reliable result
 Inexpensive
 Work and exercise
 Can be used within
hospital patients
AMBULATORY METHODS Subject wears mouthpiece
with one way valve and nose
clip or ventilated mask and
carries gas analysis
respirometer strapped to
their back
Measures oxygen
consumption calculations as
for whole body indirect
calorimetry but usually
without Co2 measurement
and hence RQ
Smaller and more compact
than Douglas bag method
Relatively simple and robust
Yields reliable results
 Useful for studies of light
to moderate
 Physical activity in near
to natural conditions

7. METHOD MEASUREMENT
PRINCIPLE
ADVANTAGES APPLICATIONS
 STABLE ISOTOPE
METHODS
 DOUBLY LABELLED
WATER
 Assesses Co2 turnover
from differential rate of
disappearance of 2H and
18O
 Calculates EE from Co2
production and an
assumption about RQ
 Gold standard method
for assessing habitual
EE in free living subjects
 Measurements over 10-
20 days
 Studies of free
living EE in all
subjects
 Especially
valuable for
children as
minimal subject
cooperation is
required
 HEART RATE
MONITORING
 Electrodes collect minute
by minute heart rate
data store on computer
chip
 EE can be calculated
from individual
calibration curves
generated for each
subject or unconverted
data can be used in semi
quantitative manner
 In expensive and easy to
use for both subject and
investigator
 Provides minute by
minute data over periods
of 7 days or greater
 Generally used for
large scale
epidemiological
studies where
comparative
values are more
important than
absolute
expenditure values
(for instance in
studies of activity
levels an health)

8. bj
METHOD MEASUREMENT
PRINCIPLE
ADVANTAGES APPLICATIONS
TIME AND MOTION
AND FRACTIONAL
METHOD
 Daily activities are
recorded by subject
themselves or by an
observer
 EE calculated by
reference to standard
tables for the energy
cost of activities
 Very important if
Subject recorded
their own activities
 Provides good data on
types of activities
 Many applications for
instance, has
frequently been used
(with field workers
during recording) to
study work and
activity patterns
among farmers etc.,
in developing
countries.
RQ= Carbon dioxide exhaled
Oxygen consumed
RESPIRATORY QUOTIENT:
Respiratory quotient is defined as the ratio of volume of Co2 produced to the volume
of O2 used on oxidation of a given amount of the nutrient.

9.  ICMR REQUIREMENTS:
 Estimation of energy requirements are derived from the measurements of individuals.
Measurements of a collection of individuals of the same gender and similar age, body size and
physical activity are grouped together to give the average energy requirement or recommended
level of dietary intake for a class of people and a population group. These requirements are
then used to predict the requirement and recommended level of energy intake for other
individuals with similar characteristics, but on whom measurements have not been made.
 In practice level of intake corresponding to mean +OR -2 standard deviation of the mean
requirement which covers 97.5% of the population chosen to define RDA. Therefore, RDA is
25% higher than the average or the mean requirement . The current RDA for healthy well
nourished Indians are calculated by using the formula

10.  ICMR has defined well nourished Indian adults who had satisfactory growth
during childhood as
 Reference man
 Reference woman
ICMR REFERENCE WOMAN
 between 20-39 years of age
 healthy and weighs 50kg.
 may be engaged 8 hours in general household work or in light industry or in any other
moderately active work. activity
 2 hours walking or active recreation orhousehold chores.
 8 hours in bed
 spends 4-6 hours sitting or moving around inlight

11. ICMR REFERENCE MAN:
 between 20 – 39 years ofage
 weighs 60 kg
 free from disease and physically fit for activework.
 employed for 8 hours
 4-6 hours sitting and movingabout
 2 hours in walking or in active recreationor household duties
 8 hours in bed

12. Age
Group
Categor
y of
work
Body
Wt Protein
Dietar
y
Fibre
*
Cal
cium
Magnes
ium Iron Zinc Iodine Thiamine
Ribo
flavin Niacin
Vit
B6 Folate
Vit
B12
Vit
C
Vit
A
Vit
D
(kg) (g/d) (g/d)
(mg
/
d)
(mg
/d) (mg/ d)
(mg
/d)
(µg/
day
)
(mg
/d)
(mg
/d)
(mg
/d)
(mg
/
d)
(µg
/d)
(µg
/
d)
(mg
/
d)
(µg
/
d)
(IU/ d)
Men
Sedentary
65 54.0
32
1000 440 19 17 150
1.4 2.0 14 1.9
300 2.2 80 1000 600
Moderate 41 1.8 2.5 18 2.4
Heavy 52 2.3 3.2 23 3.1
Women
Sedentary
55
46.0
25
1000 370 29 13 150
1.4 1.9 11 1.9
220 2.2 65 840 600
Moderate 32 1.7 2.4 14 1.9
Heavy 41 2.2 3.1 18 2.4
Pregna
nt
woman
55
+
10
+9.5
(2nd
trimester)
+22.0
(3rd
trimester)
-
1000 440 27 14.5 250 2.0 2.7 +2.5 2.3 570 +0.25 +15 900 600
Lactatio
n 0-6m
7-12m
+17.0
+13.0 - 1200 400 23 14 280
2.1
2.1
3.0
2.9
+5
+5
+0.26
+0.17
330
330 +1.0 +50 950 600

13. A sum total of energy required for BMR + SDA + Physical activity could also give us the total energy
requirement.
CALCULATING ENERGY REQUIREMENT
Particulars – adult women, 25 yr old, weight 55 Kg, height 161 cm.
 Calculate energy required for basal metabolism (BMR for female = 0.9 kcal/Kg/hr)
 BMR/day = 0.9 x 55 (wt in kg) x 24 hrs
= 1188 kcal
 Estimate level of physical activity as a percentage BMR
Activity = Energy costs as % of BMR
Sedentary = 20%
Moderate = 35%
heavy = 50%

14.  Energy cost of physical activity for a heavy worker will be = ( 50% x BMR ) +
BMR
= 50/100 x 1188 + 1188
= 1732 kcal
 Add energy cost of food intake (SDA) which is 6-10% of total calories
 On a vegetarian diet is about 6% and on a non – vegetarian diet it is about 10%,
approximately 100 kcal
 Total energy requirement = BMR + Physical activity + SDA
= 1188 + 1732+ 100
= 3070 kcal

16. FACTORS INFLUENCING ENERGY REQUIREMENT
The following factors are influence the energy requirement;
 BMR
 Age
 Gender
 Size or body weight
 Occupation
 Climate
 Lifestyle
 Health

18. BASAL METABOLIC RATE
 BMR is the total number of calories your body burns for normal bodily function, including
circulation, respiration, cell construction, digestion, temperature regulation and every other
metabolic process in body.
 The BMR is the total sum of all the energy used for basic bodily functions, encluding physical
activity
 Those basic functions usually make up the largest amount of daily calorie consumption about 2/3
 BMR is at its lowest when asleep and not digesting anything
 It can also very dramatically from person to person depending on genetics
BODY WEIGHT
 Total body weight and total body size are also major factors in the number of calories are require
 The obese person need more calorie than the normal man

19. AGE:
Calorie needs peak about age 25 and then decline by about 2% every 10 yrs.
 So if person is 25 yrs old and need 2200 calories to maintain body weight, 35 yrs. old need 2156
calories, 2113 calorie at 45, 2071 calorie at age 55
 The ageing body replaces muscle with fat which burns fewer calories than muscle does
 Staying active & doing muscle strengthening exercise keeps muscle mass in tact
 Recent works with sentor proves that can build muscle at any age
BODY SIZE
 A person smaller in size has a higher surface area per unit volume
 Thus the rate of heat loss is high
CLIMATE
The people living in cold countries need more energy to maintain body temperature
OCCUPATION
An active person requires high energy due to does a lot of heavy work

20. GENDER
 An adult man has less body fat and about 10 – 20 % more muscle than a women of the same size
and age
 Because muscle burns more calories than fat does, a man’s calorie needs are generally about 5 –
10% higher than a women’s.
 The exception for women is during pregnancy and breast feeding
LEAN BODY MASS
 Total body weight follows with the number of calories you require but sorting the total
weight into its lean and fat mass allows to calculate the calorie needs even more accurately
 The higher LBM, the higher the BMR