This document discusses energy balance and factors that affect energy requirements. It covers: 1) The main sources of energy for the body are carbohydrates, proteins and fats. Basal metabolic rate accounts for 60-75% of total energy expenditure and is affected by factors like lean body mass, growth periods, hormones, disease states, and environment. 2) Physical activity contributes 25% on average to total daily energy needs. Aerobic activities use more energy than anaerobic activities. 3) The thermic effect of food accounts for 6-10% of total energy expenditure and is higher after protein and carbohydrate ingestion than fat. 4) Formulas like Harris-Benedict are

1. ENERGY BALANCE

2. Session Objectives
Identify factors affecting energy input and output
Differentiate factors affecting energy output
Determine the body mass index and ideal body
weights
Perform calculations to estimate energy requirements

3. INTRODUCTION
Everything humans do, physical or mental
requires ENERGY.
CHO, Prot and Fats yield energy, but they are not
used equally.
CHO and Fats are the preferred energy sources
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4. TOTAL ENERGY
REQUIREMENTSENERGY INPUT
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5. BASAL METABOLIC NEEDS
BASAL METABOLIC RATE
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6. BASAL METABOLIC RATE
Energy used by the body at rest is defned as in
terms of basal energy expenditure or resting
energy expenditure.
These are measured in terms of basal metabolic
rate (BMR) or Resting Metabolic Rate (RMR)
The measurement is made with the body at
complete physical and mental rest, relaxed but
not sleep several hours after any strenuous
exercise or activity and in a comfortable
temperature and environment
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7. NOTE: BMR OR RMR MEASURE REE MR
MEASURE REE
Includes energy needed to fuel all organs while at
rest
• TEE = REE + TEF + EEPA
• REE constitutes about 60-75% of TEE
• EEPA constitutes about 25% of TEE
• TEF constitutes 6-10% of TEE
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8. FACTORS AFFECTING BMR
Body size and composition: Lean Body Mass
Lean body mass includes muscles, bones,
connective tissue such as ligaments and tendons,
and internal organs.
One of the largest contributors to overall
metabolic rate is the relative percent of lean body
mass. the more lean body mass a person has, the
higher the person’s BMR. This is caused by the
greater metabolic activity that occurs in lean tissue
vs less active tissues of fat and bone
Other factors (e.g. age, sex) are thought to
primarily infuence the metabolic rate as they relate
to the lean body mass
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9. FACTORS AFFECTING BMR
Growth Periods
During rapid growth periods, human growth
hormone stimulates cell regeneration and raises
BEE to support anabolic metabolism.
Thus, growth spurts during childhood and
adolescence refect periods of elevated BEE and
energy needs per kilogram of body weight.
As growth and the rate of cellular regeneration
slow with age, so does BMR.
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10. FACTORS AFFECTING BMR
Fever and Climate
The body’s energy expenditure is signifcantly
altered in response to changes in body
temperature.
BMR lowers rise in response to lower
environmental temperatures as the body takes
action to increase production and minimize heat
loss
Fever increases BMR by approximately 7% for
every 1°C above normal body temperature.
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11. FACTORS AFFECTING BMR
Hormonal Status
Energy expenditure is also infuenced by
hormonal secretions.
Thyroid hormone plays a signifcant role in
regulating metabolism. Individuals with an
underactive thyroid gland may develop
hypothyroidism, which results in a decreased
metabolic rate.
Growth hormone increases metabolism,
alternatively, a defciency of normal growth
hormone secretions attenuates the metabolic rate.
Other hormones (e.g. insulin, cortisol) also
increase metabolism
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12. FACTORS AFFECTING BMR
Disease State
The presence of disease may alter a patient’s
BMR. Depending on the disease, the BMR may be
increased or decreased.
Diseases such as cancer, cardiac failure, HIV,
Kidney failure increases BMR cause loss of weight
and muscles
In PEM and starvation BMR decreases in response
to the drop in energy intake and loss of
metabolically active tissues
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13. PHYSICAL ACTIVITY
Physical activity contributes to the total daily energy
expenditure. An average sedentary person expends
about 25% of his intake on physical activity
Top athletes use more per day on physical activity.
Aerobic activities such as aerobic dancing, cross
country running, bicycling tend to use more energy.
Anaerobic exercises such as weight lifting do not use
as much energy.
Spontaneous activities such as walking, climbing the
stairs, mowing the lawn, etc also tend to use more
energy
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14. THERMIC EFFECT OF FOOD
Is the increase in energy expenditure associated
with consumption of food. It can be measured for
several hours after a meal.
Thermogenesis - The production of body heat in
response to food intake and in the non-shivering
response to cold.
Heat is produced when the food we eat is
digested, absorbed, transported and metabolized
and stored
It constitute 6-10% of TEE
Fat has less TEF, followed by CHO and then
Protein
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15. FACTORS AFFECTING TEF
Diet Composition
TEF increases after protein and CHO ingestion
than after ingestion of a fatty meal
Spicy Food
Increases TEF for more than 3 hours
Cafeine & Nicotine
Increase TEF
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16. ESTIMATING ENERGY
REQUIREMENTS
Harris-Benedict Formula
Males: BEE = 66.5 +13.8 X Weight + 5 X
Height - 6.8 X Age
Females: BEE = 655.1+ 9.6 x Weight + 1.9 x Height -
4.7 X Age
TEE = BEE x SF x PAL
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17. ESTIMATING ENERGY
REQUIREMENTS
• NB: Weight in Kg, Height in cm, Age in
Years
•
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18. Determining the Body Mass
Index (BMI) and Ideal Body
Weight (IBW)
Body Mass Index
Body Mass Index=Weight (kg)/Height (M)2
<18.5 Under weight
18.5 - 24.9 Normal weight
25 – 29.9Overweight
>30 Obese
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19. IDEAL BODY WEIGHT
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1. Males: IBW = ( 20 X H2 ) — ( 25 X H2 )
2 . Females: IBW = (19 X H2 ) — ( 24 X H2 )
I. Underweight = lowest IBW + Actual weight
_______________________
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II. Overweight = lowest IBW + Highest IBW
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Obese = (Actual Body Weight - IBW X 0.25) + IBW

20. Abdominal Fat/ Waist
Circumference
The position of fat influence health and disease risk.
WHR is 0.9 or less for men and 0.8 or less for
women= Smaller waist and larger hip measurement
Waist circumference of > 88 cm in women and
> 102 cm in men indicate abdominal obesity
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21. ENERGY DISTRIBUTION
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PRUDENT DIETARY GUIDELINES
PRUDENT DIETARY GUIDELINES SOUTH AFRICAN GUIDELINES
SOUTH AFRICAN GUIDELINES
CHO : 55 - 60%
Fat : 25 - 30%
Prot : 12 - 15%
 CHO : 50 - 65%
 Fat : 25 - 30%
 Prot : 10 - 20%

22. ENERGY VALUES OF FOOD
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1g CHO = 4kcal (17kj)
1g Prot = 4kcal (17kj)
1g Fat = 9kcal (38kj)

23. CALCALCULATIONSLATIONS
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24. 1. Calculate energy of food if
the food contains 12g CHO, 8g
PROTEIN, 5g FAT
• 2. Complete A, B and C page 187
• Discuss with your mates- NB in test 2
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25. Finding a Healthy Weight
• Developing a healthy lifestyle is key
• South African Food based dietary
guidelines - Self study-NB
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