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Energy Balance
Module 4.2
Energy Balance
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• Energy balance occurs when
energy consumed equals energy
expenditure.
• Energy is measured in
kilocalories (kcal, kcalories)
– A kilocalorie is a measure of
the amount of energy that is
supplied to or expended by the
body.
1 pound fat = 3500 Calories stored.
To lose body fat, a Calorie deficit needs to be created.
To gain body weight, a Calorie excess needs to be created.
Body weight changes are based on the relationship of Caloric
(Energy) intake & Energy Expenditure.
Energy Intake and Expenditure
Energy Intake
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Protein (4 Calories per gram)
CHO 4 kcal/g
Fat 9 kcal/g gram
Alcohol 7 kcal/g
All of the Calories add up!
Energy Expenditure
Resting Energy Expenditure
(REE): similar to BMR.
• Considers amount of
energy burned at rest.
• REE can be measured in
the lab or estimated using
the Mifflin Equations.
Energy Balance Equations
• If Calories Consumed = Calories Expended
– Body weight is typically maintained. Energy balance occurs.
• If Calories Consumed > Calories Expended
– Weight is typically gained . Positive energy balance occurs.
• If Calories Consumed < Calories Expended
– Weight is typically lost. Negative energy balance occurs.
Energy Balance
Metabolic rate represents the number of calories needed to fuel
ventilation, blood circulation and temperature regulation. Calories are
also required to digest and absorb consumed food and fuel the
activities of daily life. Therefore, metabolic rate is an estimate of how
many calories you would burn if you were to do nothing but rest for 24
hours. Metabolic rate epresents the minimum amount of energy
required to keep your body functioning.
• Intake - hunger, appetite, portion vs serving size
• Expenditure
1. Basal metabolism (breathing; heartbeat)
sum of all chemical activities
2. Physical (voluntary muscles movements)
– Lean Body Mass
3. Thermic effect of food (digestion)
• specific dynamic action (SDA)
Energy Expenditure
~60%
BMR
1. BMR (REE) Energy Expenditure
Basal Metabolic Rate (BMR): (60-65%)
• The energy required by the body to minimally
function (heart to beat, lungs to breathe, …).
• BMR measurements are typically taken in a
darkened room upon waking after 8 hours of
sleep and 12 hours of fasting to ensure digestive system is
inactive, and with the subject resting in a reclined position.
• Majority of expenditure in a sedentary person.
Resting Energy Expenditure (REE): Similar to BMR.
• Determines the number of calories you burn in a 24 hour
period maintaining basic bodily functions, but also includes
the number of calories burned eating and conducting small
amounts of activity
• RMR measurements are typically taken under less restricted
conditions than BMR
• REE can be measured in the lab or estimated using the Mifflin
Equations.
The Mifflin Equations
Are based on gender, height,
weight, and age
Resting Metabolic Rate (Calories/day) =
• REE Formula For MEN:
– 10 x weight (kg) + 6.25 x height (cm) - 5 x age (y) + 5
• REE Formula For WOMEN:
– 10 x weight (kg) + 6.25 x height (cm) - 5 x age (y) - 161.
W= Weight in Kg (pounds divided by 2.2)
H = Height in centimeters (inches x 2.54)
A= Age in years
Factors Affecting BMR/REE
• Age: BMR is reduced with age.
• Gender: More lean mass means a higher BMR (gender
differences).
• Physiological State: Illness, pregnancy, lactation, stress,
metabolic diseases like hyperthyroidism can increase the
BMR. Starvation or prolonged fasting decreases BMR up to
80% in women & 60% in men.
• Environmental Temperature: Hot or cold temperatures
increase BMR.
2. Physical Energy Expenditure
Physical Activity (PA) (25-35%):
• The energy expended to perform
physical activity.
• Voluntary muscle movement.
• The total amount of energy
expended increases with body
weight and the intensity of the
exercise.
Physical Activity & Calorie Burn
• The BMR or REE can be used to determine energy spent or
Calorie burn in PA.
• Calories burned =
– Hours spent in activity x REE x An Activity Factor ÷ 24 hrs/d
Activity
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Factors
Sleeping/reclining
1
Very Light activity:
sitting, standing
1.5
Light Activity- moving
without sweating
2.5
Moderate activity –
moving and sweating
5
Strenuous- if extended
leads to exhaustion
7
3. Digestion Energy Expenditure
Thermic effect of food /
Specific Dynamic Action (SDA):
• The food processing charge.
• ~10% of the total number of calories consumed is
required for the digestion, absorption & assimilation of
nutrients into the body.
• Metabolic processes increase when
eating (chewing, swallowing);
digesting (breaking food substances
into smaller units); absorbing
(moving digested units of food
throughout the body).
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