ENERGY FROM FOOD

1. ENERGY
(FOOD &
NUTRITION)
Presented by:
Kavita Kachhawa

2. CONTENT
• Overview of energy needs
• Regulation of energy intake
• Abnormal energy status

3. Definitions
• Metabolism
• Reference men
• Reference women
• Energy

4. Metabolism
• Metabolism is a general term that encompasses
all chemical changes occurring in living organisms
Metabolic pathways:
• Catabolism: metabolic process whereby cells
break down complex substances into smaller
ones.
• Anabolism: metabolic process whereby cells
convert simple substances into more complex
ones.

5. Reference man
Reference man is between 18-29 years of age and
weighs 60 kg with a height of 1.73m with a BMI
of 20.3 and is free from disease and physically fit
for active work; on each working day, he is
engaged in 8 hours of occupation which usually
involves moderate activity, while when not at
work he spends 8 hours in bed, 4-6 hours in
sitting and moving about, 2 hours in walking and
in active recreation or household duties
ICMR 2010

6. Reference woman
Reference woman is between 18-29 years of age,
non-pregnant non- lactating (NPNL) and weighs
55 kg with a height of 1.61m and a BMI of 21.2,
is free from disease and physically fit for active
work; on each working day she is engaged in 8
hours of occupation which usually involves
moderate activity, while when not at work she
spends 8 hours in bed, 4-6 hours in sitting and
moving about, 2 hours in walking and in active
recreation or household duties
ICMR 2010

7. 1. Energy:
 Energy is the ability to do work.
 Energy is a precisely defined property of chemical
compounds and other physical systems
Units of energy:
Kcal (Kcal)
Mega joules (MJ) (IUNS)
1Kcal=4.186KJ
1MJ= 239Kcal
One kilogram calorie is the quantity of heat required to raise the
temperature of 1kg of water through 1º C from 14.5 to 15.5º C
A joule is defined as the energy required to move 1kg mass by 1
meter by a force of 1 newton.

8. • Lavoisier (1793-94) is considered as the pioneer in
studies on energy metabolism
• First law of thermodynamics is always followed:
Energy can not be created or destroyed but only
changed between its different forms
• The human body is roughly equivalent to a good
internal combustion energy of food
• The body has the unique ability to shift the fuel
mixture of carbohydrates, protein and fats to
accommodate energy needs.

9. Basic need for energy
• Maintaining body weight and good health
• Supporting growth and physical activity
• Maintaining body temperature
• Maintaining metabolic activity
Energy balance: Energy input = Energy output
Energy imbalance: Energy input = Energy output
Positive balance: Energy input > Energy output
Negative balance: Energy input < Energy output
Energy Balance

10. Energy source
• The human body utilizes the potential energy
contained in foods for maintaining life and doing work
• The energy yielding food factors are: carbohydrates,
proteins and fats
• Within the body the nutrients are oxidized in the cells
with the help of catalysts such as enzymes, co-enzymes
and hormones
Carbohydrates/fats CO2 +Water+ Energy + Heat
Proteins CO2+ Water + Urea+ Energy + Heat
Energy in food

11. Principle Equipment Purpose
Direct calorimetry
(the energy released or
expended is measured by
the heat produced)
Bomb calorimetry Energy value of food
At water rose Calorimetry Energy expenditure
during BMR/REE of at
light activity
Indirect calorimetry
(consumed O2 is directly
related to the energy
liberated as heat)
Benedict oxy calorimetry Energy value of food
Benedict Roth apparatus
• Douglas bag
• Max Plank respirometer
•Kofranyi Michaelis
respirometer
Determination of
BMR and energy
expenditure during
work
Determination of energy
Srilakshmi 2009

12. Direct Calorimetry
• Lavoisier technique
• Determination of energy use by the body by measuring the
heat released from an organism enclosed in a small
insulated chamber surrounded by water. The rise in the
temperature of the water is directly related to the energy
used by the organism
• The O2 intake, CO2 output, N2 excretion in feaces and urine
are also measured during the whole period of observation
• Expensive, complex, time consuming and laborious
• No longer widely used

13. Determination of energy in foods
Bomb calorimeter
• It measures gross energy of food
• The food stuff produces heat on combustion with
oxygen. This amount of heat can be measured in bomb
calorimeter

14. Physiological energy value of foods
• In the bomb calorimeter, carbohydrates, fats and
proteins are completely oxidized
• In real,
Loss of digestion: Atwater concluded that 99% of
ingested carbohydrates, 95% fats and 92% of proteins
are absorbed
Loss of energy in metabolism due to incomplete
oxidation: there is no loss in metabolism in the case of
carbohydrates and fats. But in case of proteins, some
extent of energy (1.2cal/gram) is lost as urea due to
incomplete oxidation.
The nitrogen present in proteins is not completely
oxidized to nitrogen oxides, which are toxic, but to urea,
which is less toxic and can be excreted in the urine. The
urea contains around a quarter of the chemical energy in
the original protein, or around 5.2kJ/g protein.

15. Gross
energy
of food
(kcal/g)
Digestible
energy
(kcal/g)
Digestibility
coefficient
Metabolizable
energy
kcal/g kJ/g
Carbohydrate 4.10 4.00 0.98 4 17
Fats 9.45 9.00 0.95 9 38
Proteins 5.65 5.20 0.92 4 17
Alcohal 7.10 7.10 7

16. Gross Energy: total heat of combustion or the total chemical energy
in the food.
Digestible Energy: the energy available after digestion is termed as
digestible energy
Digestibility coefficient: is used to express the proportion of an
ingested nutrient that ultimately becomes available to the body
Metabolizable Energy: the energy available after losses in faeces and
urine have been subtracted from the gross energy is termed as
metabolizable energy
Physiological fuel values : the amount of energy actually available to
the body from a given amount of nutrient

17. • Soluble dietary fiber and some insoluble fibre
undergo fermentation in the colon and yield
short chain fatty acids, which are utilized as
energy source by liver and colonic cells
• There is 2.6kcal/g energy is provided by soluble
fibre and no energy from non-fermentable fibre
• In conventional foods, 70% of fibre is soluble
(fermentable). So in general, in foods, energy
conversion factor for fibre is 2.0kcal/g
ICMR 2010

18. Indirect Calorimetry
• Determination of energy use by the body without
directly measuring the production of heat. Methods
include gas exchange, RQ measurement (oxygen uptake
and/or carbon dioxide output) and the doubly labeled
water technique
• Less expensive, simple, applicable to field studies and
clinical analysis
RQ of Carbohydrates= 1
RQ of Fats=0.7
RQ of Proteins=0.8
RQ of mixed diets= 0.85

19. Significance of Respiratory Quotient
• RQ helps in determination of metabolic rate
• It is the guide for assessing the type of food burning or the
nature of synthesis taking place in the whole body or in any
particular organ
• The determination of RQ aids in the diagnosis of acidosis,
alkalosis and diabetes mellitus etc
• Non protein RQ is used for calculating the total energy
output and the proportions of various food stuff being burnt

20. Benedict oxy calorimeter
Relation b/w O2 required and calorific value
Substrate 02 required Energy
1g carbohydrate 0.8 4.1
1g fat 2.2 9.5
1g protein 1.2 5.5

21. Overview of Energy Needs

22. • Individual Energy Requirement
The level of energy intake from food that balances
energy expenditure when the individual has a body
size and composition and level of physical activity,
consistent with long-term good health; and that will
allow for the maintenance of economically essential
and socially desirable activity.
in children and pregnant and lactating women, the energy requirement
includes the energy needs associated with deposition of tissues or the
secretion of milk at rates consistent with good health
FAO/WHO/UNO 1985

23. Assessment of Energy Requirement
• Energy requirement must be assessed in terms of
energy expenditure rather than in terms of
energy intake.
• Energy expenditure from a physiological point of
view is made up of three major components:
1. Basal Metabolic Rate
2. Regulatory thermogenesis
3. Physical activity
For all activity purposes, the component
energy expenditure related to regulatory
energy output or thermogenesis are
known to merge into measurements
related to cost of physical activity.
1.Basal metabolic rate
2.Physical activity
ICMR 2010

24. Energy expenditure approach
• Is more reliable
• May not vary widely due to day to day or week to
week changes
• Not depend on eating habits or food groups as
compared to energy intake approach
• Factorial approach: In this approach, the nutrients
required for different functions, are assessed
separately and added up to arrive at the total daily
requirement. This has been the basis of computing
the energy requirement. (viz., sleep + rest +
occupational activity + non-occupational activity).

25. Basal metabolic rate
• The largest single component of 24 hour energy expenditure is usually the BMR
• Basal metabolic rate (BMR) is the amount of energy required to carry on the involuntary
work of the body
• It includes the functional activities of the various organs such as brain, heart, liver,
kidney and lungs. The secretary activities of glands, peristaltic movement gastro
intestinal tract, oxidation occurring in resting tissue, maintenance of muscle tone and
body temperature.
• The brain and nervous tissue account for 1/8 of the energy utilized at the basal state
and the lungs, liver, heart and kidney for additional 3/5th .
• used during 24 hours while subject is lying at physical and mental rest in a thermo
neutral environment (that prevents the activation of heat-generating processes, such as
shivering) at least 12 hours after the meal.
• The BMR remains remarkably constant on a daily basis, typically representing 60-70% of
total energy requirement.

26. Resting energy expenditure
• The REE is basically a combination of basal energy
needs, plus the thermic effect of food plus a small
amount of energy needed to perform the most
sedentary activities such as sitting quietly
• RMR is likely to be a little higher than BMR, while
energy expenditure during sleep may be 5-10% below
the BMR.
Miffin-St. Jeor Equation:
Males (kcal/day) = 10(wt)+6.25(ht)-5(age)+5
Females (kcal/day) = 10(wt)+6.25(ht)-5(age)-161

27. Factors affecting BMR
• Body size
• Sex and age
• Body composition
• Climate
• Under nutrition and
starvation
• Sleep
• Fever
• Physical activities
• Specific dynamic
action of food
• Fear and nervous
tension
• Thyroid
• Adrenaline
• Anterior pituitary
• Other diseased
condition
• Pharmacological
agents

28. Determination of BMR
Benedict and Roth Apparatus

29. Equations for estimating BMR
Harris-Benedict Equation
Males = 66.5+(13.75 X W) +(5 X H) – (6.75 X A)
Females = 655.5+(9.56 X W)+(1.85 X H)-(4.68 X A)
Wt(kg), ht(cm), Age (Years)
Body weight
For females= W x0.9 kcal x 24 hours
For males = W X1kcal X 24 hours
Metabolic body size
70 X Wt in Kg(3/4)
SRILAKSHMI 2009

30. FAO/WHO/UNU equation
For females: 8.7XW+829
For males : 11.6XW+879
Sex Age ICMR Equation
Male 18-30 14.5XW+645
30-60 10.9XW+833
>60 12.8XW+463
Female 18-30 14.0XW+471
30-60 8.3 XW+788
>60 10.0XW+565

31. Thermogenesis
• Postprandial thermogenesis (PPT)
• Thermal effect of food (TEF)
• Specific dynamic action of food (SDA)
• Heat increment of feeding
• It represents the energy used for digestion, absorption,
transport and storage of the ingested nutrients, as well as
any increase in activity or arousal associated with eating.
• It is assumed to be around 10% of the total energy
expenditure(TEE)
• TEF peaks about one hour after eating and normally
dissipates within five hours
Anonymous

32. Diet-induced thermogenesis (DIT): is usually
used to describe the longer-term effects of
diet on energy expenditure
Cold-induced thermogenesis: includes both
shivering and non-shivering thermogenesis
NEAT: non exercise activity thermogenesis
is the thermogenesis that accompanies
physical activities other than volitional
(intentional) exercise such as the activities of
daily living, fidgeting, spontaneous muscle
contraction and maintaining posture when
not recumbent
Anonymous

33. Physical activity
• Physical activity accounts 20-40% of total daily expenditure in
most individuals
• It includes work, leisure activities and other everyday activities
• The energy expended in activity depends on the type, duration
and intensity of activity
• There is a wide variation in the energy cost of any activity both
within and between individuals, due to differences in body size
and the speed and agility with which an activity is performed
• To compensate for differences in body size, it is now common to
express the energy costs of activities as multiples of BMR/RMR

34. Physical activity ratio
• Physical activity ratio (PAR) is expressed as the
ratio of the energy cost of an individual activity
per minute to the cost of the basal metabolic
rate (BMR) per minute.
Energy cost of an activity
per minute
Physical Activity Ratio (PAR) =
Energy cost of basal
metabolism per minute

35. Physical Activity Level (PAL)
LEVEL OF
ACTIVITY
ICMR 1989 ICMR 2010 FAO/ WHO/ UNU
Sedentary Work 1.6 1.53 1.40-1.69
Moderate Work 1.9 1.8 1.70-1.99
Heavy Work 2.5 2.3 2.0-2.40*
PAL: PAR/24

36. Determination of energy requirements
• Direct Calorimetry
• Indirect Calroimetry
• Doubly Labeled Water (DLW) Method
• Heart Rate Monitor (HRM) Method
• Factorial method

37. Doubly Labeled Water (DLW) Method
• Most accurate technique for measuring TEE in free living
individuals
• TEE measured by this method includes BMR, metabolic
response to food, thermoregulatory needs, physical
activity costs and energy cost of synthesis of growing
tissues
• A method for measuring daily energy expenditure over
extended time periods, typically 7 to 14 days, while
subjects are living in their usual environments
• Non-invasive and non-obtrusive
• Expensive, not widely available
Mahan et al 2012

38. Small amounts of water that is isotopically labeled with deuterium
and oxygen-18 is inoculated
Energy expenditure can be calculated from the difference between
the rates at which the body loses each isotope

39. Heart Rate Monitor (HRM) Method
 Heart rate monitor is an electronic device that can
accurately record minute-to-minute heart rate under free
living conditions, for a whole day or more
 The mean TEE measured with this technique is
comparable to mean value obtained using Doubly
Labeled Water or whole body calorimeter.

40. factorial method
• Calculate BMR
• Calculate the activity costs over a 24 hours period
• Add 1+2 and calculate 10% thermic effect of food
• Calculate total energy by adding BMR+ activity needs
+ thermic effect
• Ex: 25 aged male having 60 kg weight,
1. 14.5XW+645= 14.5X60+645= 1515Kcal
2. BMR unit for moderate activity 1.8 (included thermic effect
of food)
3. 1.8 X1515= 2727kcal
Srilakshmi 2009

41. Estimation of energy requirement for
Indians
• BMR of Indians is about 5% lower as compared to
reported BMR of developed countries
• The minimum energy requirement for maintaining the
BMR is 1400Kcal
• Daily energy requirement (MJ/d) for Indian infants is
calculated from analysis of total energy expenditure on
weight, plus allowance for energy deposition in tissues
during growth.
• The weight gain during growth and overall energy
requirement taking growth into consideration for boys
and girls at childhood stage.

42. • Energy requirement during pregnancy comprises the
normal requirement for an adult woman and an
additional requirement for foetal growth plus the
associated increase in body weight of the woman
during pregnancy, most of which occurs during the
second and the third trimesters. The total energy
requirement during pregnancy for a woman weighing
55 kg is estimated to be 80,000 kcal of which 36,000
kcal is deposited as fat, which is utilized subsequently
during lactation.
• Energy cost of lactation is determined by the breast
milk output and its energy content
• The efficiency of utilization of milk energy is 80%

43. Regulation of food intake
• Internal and external cues help the body regulate
food consumption and maintain energy equilibrium
• Internal cues: interactions and feedback
mechanisms among hormones and hormone like
compounds and organ system
• External cues: sight, smell and taste of food
• Internal and external cues work together to ensure
that we eat enough to survive. However the
complex interplay of these cues makes it difficult to
identify specific factors that cause overeating and
obesity or disordered eating.
Swaminathan 2006

44. • Hunger: the internal physiological drive to find and consume
food. Hunger as a negative, uneasy and painful sensation
arise in stomach resulting from lack of food. Hunger is
satisfied by eating of food
• Appetite: a pleasure sensation which causes in human beings
the psychological desire for a particular food is called appetite
• Phagia: eating/swallowing
• Satiation: feeling of satisfaction and fullness that terminates a
meal
• Satiety: feeling of fullness of stomach that quells the desire
for food and cessation of urge to eat. Satiety determines the
interval between meals Anonymous

45. External Cues
1. Diet composition: based on energy density of food
Protein appears to makes a stronger contribution to satiety than fats and
carbohydrate
Bulkier foods have high amount of fibre and water, also have a higher satiety value
2. Sensory properties: flavor, texture, color, temperature, presentation and taste
of food
Taste is usually the reason for choosing a particular foods
3. Portion size: tend to respond visually to the amount of food on a plate rather
than paying attention to internal feelings of satiation
4. Environmental and social factors: tendency of eating more in cold weather as
comparative to hot weather
Plate size, dim light and socializing are other factors that influence consumption
5. Emotional factors: eating can provide a powerful distraction from lonliness,
anger, boredem, anxiety, shame, sadness, inadequacy, low moods, low self
esteem, low energy levels
Anonymous

46. Internal cues
2. Neurological and hormonal factors:
50 different chemicals are involved in the regulation of feeding
NPY ( Neuropeptide Y) A
Neurotransmitter widely distributed throughout the brain and peripheral
nervous tissue
Powerfully stimulates appetite
NPY activity linked to eating behavior, depression, anxiety and cardio vascular
function
Ghrelin: (hunger hormone):
Hormone produced in stomach that stimulates feeding
Leptin: satiety hormone:
produced by fat cells that signals the amount of body fat content and influences
food intake
Leptin signals the pathway that enhances energy production to keep body
weight in normal range
1. Gastrointestinal sensations: filling food in stomach supress urge of food
Even taste, salivation, chew and swallow diminshes hunger for 20-40 minutes as the
brain measures the passage of food
Anonymous

47. Regulation of energy intake
The physiological mechanisms involved in hunger, appetite
and satiety and in the regulation of food intake are
discussed here:
• Regulatory mechanisms
• Nervous regulation
• Role of hypothalamus
• Glucostatic regulation
• Effect of free fatty acids and amino acids level in blood
• Thermostatic regulation
• Lipostatic regulation
• Metabolic difference in genetic and hypothalamus obesity
Regulation of food intake
Swaminathan 2006

48. Regulatory mechanisms
• Biometric regulation: It sets limits to the maximum and
minimum energy metabolism of an individual
It is the result of a necessity imposed by the structure of the
animal or human body
• Short term regulation: Day to day regulation of energy output
It adjusts energy intake to requirements
Thermostatic and glucostatic mechanisms are related to short
term regulation
• Long term regulation: It corrects the errors of the short
mechanism involving either excessive or deficient intakes by
successive compensations of eating more or less on the
successive days
The long term regulation appears to function through a lipostatic
mechanisms

49. Nervous Regulation
• Responsible for the different
types of feeding behavior such
as habits, prejudices, likes,
dislikes, etc.
Neocortex
• Cerebral structure may influence
food intake
• limbic structure in the frontal and
temporal lobes regulate food
intake by a discriminating
mechanism termed “Appetite”
Limbic
system

50. Role of Hypothalamus
• Satiety centre: located in ventromedial area of
hypothalamus
This centre acts as a break on the feeding centre
• Feeding centre: : located in lateral area of
hypothalamus
Increase in blood glucose level caused activation
of satiety center while lowering of blood glucose
level increased activity of feeding centre by
encephalographic waves

51. Glucostatic regulation
• Effect of blood glucose level on satiety and feeding centers
in the hypothalamus
• Effect of blood glucose on hunger contractions:
Saturated blood glucose level leads to inhibition of
stomach contractions as well as hunger sensations
• Effect of glucagon on hunger contractions
Glucagon increase both blood glucose and glucose reserves
which acts on the satiety center and eliminates hunger
sensations

52. Thermal stimuli
• Environmental temperature have long term effect
regulation on food intake
• Hypothalamic centers are very sensitive to the
temperature of the blood. Rise in blood temperature
stimulates the satiety centre and a fall in blood
temperature stimulates the feeding centre.

53. Lipostatic regulation
• Lipostatic control is involved the long term regulation of
food intake and body weight
• The maximum body weight attained depends on many
physiological characteristics of the body composition such
as: diet, strain, exercise, regime etc
• The quantity of body fat metabolized daily is proportional,
within each type, to the size of fat depots and a constant
proportion of the depot fat is metabolized depending on
the total body fat content

54. Abnormal energy status
• Under nutrition • Over nutrition

55. Under nutrition: is defined as the outcome of insufficient
food intake and repeated infectious diseases. It includes
being underweight for one’s age, too short for one’s age
(stunted), dangerously thin for one’s height (wasted) and
deficiency of vitamins and minerals
Over nutrition: a condition of excess nutrient and energy
intake over time. Over nutrition may be regarded as a
form of malnutrition when it leads to morbid obesity.
Obesity: is defined by the World Health Organization as
“abnormal or excessive fat accumulation that may impair
health”

57. WHO 2010

58. The 13 Lancet Interventions
promoting breastfeeding
exclusive breastfeeding for the first six months
complementary feeding
better hygiene
zinc supplementation
giving zinc to manage diarrhoea

59. providing vitamin A through fortification or supplementation
universal iodization of salt
multiple micronutrients supplements
providing iodine through iodization of salt
providing iron folate supplementation
providing calcium supplementation
treatment of severe acute malnutrition with special foods

61. Obesity
Criteria Genetic obesity Regulatory obesity
Etiology Obese
hyperglycemic syndrome
(metabolic)
Obesity due to
hypothalamic injury
Physical activity Low Normal
Pathology and mechanism Hyperplasia of islets of
Langerhans, increased
secreation of insulin and
glucagon
Hypothalamic lesions or
destruction of satiety centre
Effect on food intake Moderate hyperphagia Severe hyperphagia
Energy balance Positive Highly positive
Weight gain Excessive Excessive
Effect of starvation on
obesity
Loss of adipose tissue is not
uniform
Body composition become
normal
Blood glucose level Hyperglycemic Normal
Adipose tissue metabolism Lipogenesis from acetate
increased
Lipogenesis from acetate
increased
Swaminathan 2006

62. Leptin resistance in obesity
• In obese people, levels of leptin found in the blood are normally
very high and more than sufficient to suppress the appetite and
increase the metabolism
• The high sustained concentrations of leptin from the enlarged
adipose stores result in leptin desensitization. These people are
said to be resistant to the effects of leptin
• The pathway of leptin control in obese people might be flawed
at some point so the body does not adequately receive the
satiety feeling subsequent to eating
Padioetis et al 2011

63.  normal metabolism
 Leptin-resistance
 Diabetes mellitus
 Poor immune
function
Obesity
Ob gene
Leptin
Excess Leptin
Disregulation of Leptin Signaling
Normal

64. Consequences of obesity

65. References
• Swaminathan M (2006) Food and Nutrition vol 1. The Bangalore Printing and
Publishing Co. Ltd., No. 88, Mysore Road, Bangalore-560 018
• Srilakshmi (2009) Energy metabolism . Nutrition Science IIIrd ed. new age
international publishers Pp 67-91 .
• Mahan L K, Stump S E, Raymond J L ( 2012) Intake energy. Food and the nutrition
care process. Pp 19-29. Elesvier 13 ed.
• Padiotis K, Samara V , Paralikas T (2011) Obesity leptin and the immune system.
Interscientific health care 3(2) 44-51.
• ICMR (2010) Nutrient requirements and recommended dietary allowances for
Indians. National Institute of Nutrition , Indian Council of Medical Research ,
Jamai-Osmania PO, Hyderabad – 500 604
• Anonymous