Quantifying Energy Expenditure Flashcards
How is Total Energy Expenditure (TEE) calculated?
Total Energy Expenditure = Basal Metabolic Rate (BMR) + Dietary Induced Thermogenesis (DIT) + Energy Of Physical Activity Levels (PAL) + Others
TEE = BMR + DIT + PAL + Others
Explain what Energy of Physical Activities includes
Anything outside of a basic functioning
Explain what Dietary induced thermogenesis includes
The production of heart that occurs after eating which contributes to the body’s resting metabolic rate
Explain what Basal Metabolic Rate includes
The number of calories you burn as your body performs basic (basal) life-sustaining function
What is Basal Metabolic Rate (BMR) also referred to as?
Resting Energy Expenditure (REE)
Stress is also a component of energy expenditure. What things are classed as stress?
Burns
Wounds
Infection
How is Resting Energy Expenditure (REE) calculated?
REE is measured as physical and mental rest, laying down, after an overnight fast of at least 10 hours with no stimulants of vigorous activity in the past 24 hours.
What type of calorimetry is used to measure Resting energy expenditure (REE)
Indirect Calorimetry
How is Energy Balance Measured?
Energy Balance = Energy Intake - Energy Expenditure
How is Energy Intake Measured?
Energy Intake = Energy Expenditure + Total Energy Stores
When would Energy requirements increase?
Weight Gain
Growth
Pregnancy
Training
Illness and Disease
When would Energy requirements decrease?
Weight Loss
Loss of appetite
Post-training
End of Life
Name the 3 ways energy expenditure is measured
Direct Calorimetry
Indirect Calorimetry
Prediction Equation
Rank the methods of energy expenditure based on accuracy from most accurate to least accurate
Direct Calorimetry
Indirect Calorimetry
Prediction Equation
Rank the methods of energy expenditure based on complexity from most complex to least complex
Direct Calorimetry
Indirect Calorimetry
Prediction Equation
Explain how direct calorimetry works
The subject is placed in an insulated box/room/chamber
The heat produced by the subject warms the area
Temperature increase in measured
In the chamber: Cold water in, air in (O2), air out (CO2), heated water out
What does direct calorimetry measure and give limitations?
Heat production
But no indication of substrate utilization (fat, carbohydrate) during exercise
Explain what indirect calorimetry is based upon
Based on the relationship between O2 uptake and CO2 production.
What can indirect calorimetry be used for?
By measuring O2 uptake and CO2 production, we can calculate the energy expended = Respirometry
Give the types of indirect calorimetry (gas collection)
Room Calorimetry (ventilated chamber)
Metabolic cart (mouthpiece, mask or hood)
Portable respirometry (Douglas bag, IMP, oxylog)
Doubly-labeled water
Explain how indirect calorimetry works with a ventilated chamber
Air is drawn through the chamber at a measured rate
The concentration of O2 and CO2 is measured accurately in air entering and leaving the chamber
Temperature and pressure recorded
Uptake of O2 and production ofCO2 calculated
Estimated energy calculated using a formula
What things do portable respirometry require?
System to collect inspired/ expired air
Measurement of volume
Analysis of O2 and CO2 concentration
Calculation
Name 3 types of portable respirometry technology
MedGem
BodyGem
Ecal
Explain the principle of doubly labeled water
Stable isotope given to subject 2H2 18O - Deuterium = 2H2 , Oxygen-28 = 18O
Both isotopes mix with a pool of body water
The rate of each isotope’s disappearance from the body is measured
18O is lost more quickly as two ‘escape routes’
The difference in the rate of loss used to calculate CO2 production
Cos = (0.5 x TBW) x (rate 2H loss - rate 18O loss)
Calculate energy expenditure from CO2 production
Explain the method for using doubly labeled water to measure the energy expenditure of a subject
The subject drinks an accurate dose of doubly labeled water
Sample saliva or urine daily for 1-2 weeks
2H lost as water (urine/breath), 18O lost as water and CO2
Measure the rate of constants for the disappearance
Differrence = CO2 production
rC02 is used to calculate energy expenditure
What are prediction equations based on
Body composition, age, sex, disease, injury
If the above factors, it can predict BMR (Basal metabolic rate) or REE (resting energy expenditure)
Large studies 100’s - 100’s subjects
Data collected and standard equations produced
Equations vary depending on the population
Give the Harris-benedict equations used to calculate BMR for Male and Female and give units
BMR Male = (10 x weight) + (6.25 x height) - (5 x age) + 5
BMR Female = (10 x weight) + (6.25 x height) - (5 x age) -161
Weight = kg
Height = cm
Age = yrs
BMR = kcal
How is PAL (Physical activity level) calculated?
BMR X an appropriate factor for the amount of activity that a person does
Name the 4 categories of lifestyle and give the PAL level
Sedentary - 1.40 to 1.69
Moderately active - 1.70 - 1.99
Vigorously active - 2.00 - 2.40
Extremely active - greater than 2.40
