Post on 08-Apr-2018
8/7/2019 Lec4.MeasEnergy.student
1/19
Professor V. Katch MVS 110: Measurement of Energy
Expenditure
Measurement of Human Energy
Expenditure Understand the following:
Heat of combustion (Calories)
Atwater factors How to measure kCal
Quantify energy release in metabolism
Quantify food mixture metabolized
8/7/2019 Lec4.MeasEnergy.student
2/19
Professor V. Katch MVS 110: Measurement of Energy
Expenditure
What is a Calorie?
A measurement of food energy
Quantity of ____ necessary to raise thetemperature of 1 ___ (1 L) of water 1 degree
___ (from 14.5 to 15.5C) If a food contains 300 kCal then releasing the
potential energy trapped within this foodschemical structure increases the temperture of
300 L of water 1C. Different foods contain different amounts ofheat energy.
8/7/2019 Lec4.MeasEnergy.student
3/19
Professor V. Katch MVS 110: Measurement of Energy
Expenditure
How to Measure Calories?
The Bomb Calorimeter
Figure 1. Bomb calorimeter directly measures the energy value of food.
8/7/2019 Lec4.MeasEnergy.student
4/19
Professor V. Katch MVS 110: Measurement of Energy
Expenditure
Heat of Combustion
The heat liberated by oxidizing (burning)food in a bomb calorimeter represents its
_______ ____ _______ or total energyvalue of the food.
Average heats of combustion
CHO = 4.2 kCalg-1
Lipid = 9.4 kCal g-1
Protein = 5.65 kCalg-1
8/7/2019 Lec4.MeasEnergy.student
5/19
Professor V. Katch MVS 110: Measurement of Energy
Expenditure
Net Energy Value of Foods
Gross energy value from the bomb calorimeter
are different than what happens in the body.
Net energy values equal what is available to thebody after digestion:
CHO =
Lipid = Called Atwater factors
Protein =
8/7/2019 Lec4.MeasEnergy.student
6/19
Professor V. Katch MVS 110: Measurement of Energy
Expenditure
Energy Value of What You Eat
Calculate energy value of a meal
Atwater factor x food grams = total kCal
Go through an example for 100 g of food thatcontains 4% protein (4 g), 13% fat (13 g) and21% CHO (21 g).
[(4 x 4.0) + (13 x 9.0) + 21 x 4.0)]
[16 + 117 + 84 = 217 kCal
8/7/2019 Lec4.MeasEnergy.student
7/19
Professor V. Katch MVS 110: Measurement of Energy
Expenditure
Measuring Human kCal Production
CA LO RIM ET RY
Direct Indirect
CO2 +N2 Balance
Oxygen Consumption
Open Circuit ClosedCircuit
MET ABOLISM
8/7/2019 Lec4.MeasEnergy.student
8/19
Professor V. Katch MVS 110: Measurement of Energy
Expenditure
Measuring Human kCal Production
INDI T L I T D I T L I T
U ITH H T
2
FOODSTUFF + OXYGEN > HEAT + CO2+ H2O
8/7/2019 Lec4.MeasEnergy.student
9/19
Professor V. Katch MVS 110: Measurement of Energy
Expenditure
Measuring Human kCal ProductionDirect Calorimetry [Atwater-Rosa]
8/7/2019 Lec4.MeasEnergy.student
10/19
Professor V. Katch MVS 110: Measurement of Energy
Expenditure
Indirect CalorimetryMeasuring VO2 uptake
[Closed Circuit Method]
Positive:Negative Aspects
8/7/2019 Lec4.MeasEnergy.student
11/19
Professor V. Katch MVS 110: Measurement of Energy
Expenditure
IndirectCalorimetry
[Measure VO2 uptake]
Open Circuit Method
Positive:Negative Aspects
8/7/2019 Lec4.MeasEnergy.student
12/19
Professor V. Katch MVS 110: Measurement of Energy
Expenditure
Direct v Indirect Calorimetry
Calorific Transformation for Oxygen
For every liter (L) of oxygen consumed, 5kCal of energy are transformed
Thus, indirect calorimetry is a goodmeasure of heat production
8/7/2019 Lec4.MeasEnergy.student
13/19
Professor V. Katch MVS 110: Measurement of Energy
Expenditure
What Food is Metabolized?
The Respiratory Quotient (RQ)
RQ =
Every food substance has a specific RQ
8/7/2019 Lec4.MeasEnergy.student
14/19
Professor V. Katch MVS 110: Measurement of Energy
Expenditure
RQ for CHO
RQ =
C6H12O6 + 6 O2 > 6 CO2 + 6 H2O
8/7/2019 Lec4.MeasEnergy.student
15/19
Professor V. Katch MVS 110: Measurement of Energy
Expenditure
RQ for Lipid
RQ =
Between 0.69 and 0.73
8/7/2019 Lec4.MeasEnergy.student
16/19
Professor V. Katch MVS 110: Measurement of Energy
Expenditure
RQ for Protein
RQ =
8/7/2019 Lec4.MeasEnergy.student
17/19
Professor V. Katch MVS 110: Measurement of Energy
Expenditure
RQ for Mixed Foods
RQ =
8/7/2019 Lec4.MeasEnergy.student
18/19
Professor V. Katch MVS 110: Measurement of Energy
Expenditure
Thermal Equivalent of Oxygen
for the RQ RQ = 0.70 = 4.686 kCal per L O2
RQ = 0.84 = 4.85 kCal per L O2
RQ = 1.0 = 5.05 kCal per L O2
8/7/2019 Lec4.MeasEnergy.student
19/19
Professor V. Katch MVS 110: Measurement of Energy
Expenditure
Liters of Oxygen and kCals
1 Liter per min OxygenConsumed
5 kCal per min HeatLiberated
250 mL per min OxygenConsumed
1.25 kCal per min heatliberated
At Rest