Assessing Energy Metabolism Flashcards
3 components that add up to equal TEE:
- BMR
- TEF
- PA
BMR:
- basal metabolic rate
- the minimum amount of energy the body uses at rest to fuel basic cellular-level metabolic activities and to keep the heart, lungs, kidneys, and other organs functioning
TEF:
- thermic effect of food
- the amount of energy utilized in the digestion, absorption and transportation of nutrients
PA:
- includes the additional EE above BEE and TEF due to muscular activity and comprises minor physical movements (such as fidgeting) as well as purposeful gross muscular work or physical exercise
- EAT & NEAT
60-75% of TEE:
BMR
15-30% of TEE:
PA/AT
10-15% of TEE:
TEF
1600’s experimental scientists were able to prove that….
- respiratory gas exchange represented combustion
- organisms produced heat, require oxygen for life, combusted food as they released heat
- human + oxygen –> CO2 + H20
Who was first to document direct calorimetry, and what is it?
- Lavoisier
- the heat production of living organisms
Lavoisier used an ____ _____ in which he measured the ____ and ____ produced by a ____ ____.
- ice calorimeter
- CO2
- heat
- guinea pig
How was Lavoisier’s research with calorimetry important?
provided the impetus to directly measure EE during rest and PA
Direct calorimetry is done under ____ ____ conditions in _____ ____ that measure changes in _____ associated with the _____ released by a subject.
- controlled laboratory
- insulated chambers
- temperature
- heat
Describe human direct calorimetry:
- subject is placed in a sealed insulated chamber with an oxygen supply
- a known volume of water is circulated through a series of pipes located at the top of the chamber
- heat produced and radiated by the individual is absorbed by the circulating water
- the change in water temp. reflects the metabolic energy (calories) released by the subject
Calorie =
the amount of heat energy needed to raise the temperature of 1 g of water by 1 degree celsius
Direct measurement of heat production in humans has considerable ____ ____, but limited _____ ____.
- theoretical implications
- practical application
Pitfalls of direct calorimetry:
- expensive
- technically difficult
- formidable engineering expertise
- limitations placed on a subject’s mobility
- not for large scale or population studies
Indirect calorimetry:
measuring EE by measuring a proxy of heat loss such as O2 consumption or CO2 production during rest and steady-state exercise
Fuel + O2 –>
CO2 (indirect calorimetry) + H20 + heat (direct calorimetry)
Indirect calorimetry assumes that metabolic rate can be estimated by ….
measuring the rate of transformation of chemical energy into heat
In indirect calorimetry, the amounts of ____ and ____ exchanged in the lungs closely represent the ___ and _____ of these substances by the ___ ____.
- O2 and CO2
- use
- release
- body tissues
Indirect calorimetry: measuring a person’s ____ uptake during activities, researchers obtain an ____ yet _____ estimate of EE.
- oxygen
- indirect
- accurate
2 common methods of indirect calorimetry:
- closed circuit
- open circuit
Closed circuit =
respiration chamber
Open circuit =
- expired gas analysis
- carbon/nitrogen excretion
- isoptically labelled water
- respiration chamber
Respiration chamber:
- subject placed in closed space with CO2 and moisture absorbers, quantity of O2 used by the subject is measured
- subject often breaths from reservoir containing pure oxygen and as subject exhales CO2 is removed by soda lime
With the respiration chamber, decrease in ___ ____ in the closed circuit system is related to the rate of _____ ______.
- gas volumes
- oxygen consumption
Indirect calorimetry was developed when?
in the late 1800’s
Indirect calorimetry is still used where?
- hospital settings
- specialized nutrition research centres
Pitfalls of indirect calorimetry (closed):
- subject must remain close to bulky equipment
- not useful during heavy breathing episodes (ie. exercise) CO2 removal becomes inadequate
Indirect calorimetry (open): Step 1: The subject breathes from the _____ and expires into a separate outlet
or the subject inspires and expires to a stream of ____ ____. In both, the flow
of air is measured either on the ___ or ____ side of the subject and is either
____ ____ or ____ ____ for analysis of gases.
- atmosphere
- passing air
- inlet
- outlet
- collected periodically
- sampled continuously
Indirect calorimetry (open): Step 2: This gas volume is then corrected for standard conditions and is analyzed for its \_\_\_ and \_\_\_ content with subsequent calculations being done to determine \_\_\_\_ \_\_\_\_ and \_\_\_ \_\_\_\_\_.
- standard conditions
- O2 and CO2
- oxygen consumption
- carbon dioxide production
With indirect calorimetry (open), the amount of ____ that the subject is using is directly reflected by …
- energy
- the differences in O2 and CO2 levels between the inspired and expired air
VE:
- ventilator rate (L/min)
- the rate of breathing adjusted for standard environmental conditions
Standard environmental conditions:
- STPD
- standard temperature
of 08 C - barometric pressure of 760 mm Hg
- no water vapour [dry]
VO2:
- O2 consumption (L O2/min)
- litres of O2 per minute used by the body (corrected for STPD)
VCO2:
- CO2 production (L CO2/min)
- litres of CO2 per minute produced by the body (corrected for STPD)
RQ:
respiratory quotient (VCO2/VO2)
What is used to calculate VE, VO2, VCO2, RQ?
raw measurements of breathing rate and gas concentrations
EE (kJ/day) =
16.62 VO2 + 4.51 VCO2
Indirect calorimetry (open) was developed when?
late 1800’s
Indirect calorimetry (open) is still used where?
- hospital settings
- specialized nutrition research centres
Pitfalls of indirect calorimetry (open):
- reliability
- accuracy
DLW:
- doubly labeled water
- non calorimetric
- accurate and precise method for measuring TEE of free living subjects
DLW method is based on the principles of ____ ____.
isotope dilution
The DLW accuracy is ____% compared to IC, and it is also considered a ____ ____.
- 97-99%
- gold standard
DLW method considers that the ___ turnover is determined by the ___ ____ ___ and the inspired ___ and expired ____, while the ____ turnover is determined exclusively by the ….
- O2
- body water flow
- O2
- CO2
- H2
- water flow through the body
DLW step 1:
A pre-established volume and concentration of the H2 and O18 isotope is orally administered, which diffuses
throughout the body over 2 to 6 hours
DLW step 2:
As the energy is spent by the body, CO2 and H20 are produced
DLW step 3:
The CO2 is eliminated by the lungs, and the H20, by lungs, skin and urine
DLW step 4:
The H2 and O18 disappearance rate is determined by measuring repeatedly their concentrations in the body fluids (saliva, urine or blood)
DLW step 5:
The difference between the disappearance rate of the two isotopes is used to estimate the CO2 production rate and, thus, determine the EE, based on the equation of Weir
DLW is considered safe because…
- uses deuterium (H2) and oxygen18 (O18)
- non-radioactive elements which are naturally found in
human body
Pitfalls of DLW:
- expensive
- requires sophisticated equipment
- highly trained personnel
- does not provide direct information of performed physical activity and substrate oxidation
BMR is the minimum amount of energy that a body requires when lying in ____ and ____ rest.
- physiological
- mental
BMR is measured under _____ conditions, conducted with the subject in a _______ state (fasted for at least ___ hours), at complete rest in a ______ environment.
- standardized
- postprandial
- 12
- thermoneutral
The main determinant of BMR is ….
- body weight
- body composition
Since BMR is technically difficult to measure, ____ is often used, which is slightly ____ than BMR.
- resting metabolic rate (RMR)
- higher
BMR is often ____. Why is this a problem?
- predicted
- equations specific to different populations
- problematic as wide individual variation in BMR
TEF is the EE component related to the energy required for the _____, _____, _____, and ____ of nutrients after food intake.
- digestion
- absorption
- usage
- storage
TEF plays an important role in the regulation of ____ _____ and of ____ ____.
- energy balance
- body weight
TEF impact on TEE varies according to the type of _____ intake:
- macronutrient
- 0-3% for lipids
- 5-10% for cabs
- 20-30% for proteins
TEF can be divided into 2 distinct phases:
- cephalic phase
2. gastrointestinal phases
Cephalic phase of TEF:
sympathetic nervous system action
Gastrointestinal phases of TEF:
characterized by ATP consumption during the absorption and utilization of nutrients
AT:
- activity thermogenesis
- PA
- most variable component of EE in humans
AT includes the the additional EE above ____ and ____ due to ____ activity and comprises minor ____ ____ (such as fidgeting) as well as purposeful ____ ____ ____ or _____ ____.
- BMR
- TEF
- muscular
- physical movement
- gross muscular work
- physical exercise
AT is the sum of all daily physical exercise (____& ____).
- EAT
- NEAT
____ ____ techniques are the most common measure of PA because of the…
- self - report
- low financial cost
- low participant burden
Activity ____, including ____ and _____, are the most common tools for the assessment of PA.
- questionnaires
- interviews
- diaries
AT methodology pros and cons:
- cheap, allows application in large populations
- reliability and validity of the measurement of habitual PA by questionnaires is low
Moderate PA is defined as ____ METs.
3-6
Moderate to vigorous PA is defined as ____ METs.
> 3 METs
Vigorous PA is defined as ____ METs.
> 6 METs
1 MET is equivalent to…
- 1.0 kcal/kg x h
OR - 4.184 kJ/kg x h
____ ____ monitoring is one of the first _____ methods for the assessment of PA.
- HR
- objective
____ ____ are the most promising for the assessment of PA. Sensors can be applied in ____ ____ subjects over prolonged periods of time. When equipped with a data memory to store info on ___ ___, they can also be used to study ____ of PA in time.
- motion sensors
- free-living
- body movement
- patterns
Accelerometers can provide information about the total _____, the _____, the _____ and the _____ of PA.
- amount
- frequency
- intensity
- duration
Indirect measurement of AT:
- a PA level defined as TEE:BMR (ie. no TEF) needed
- most common
PAL =
TEE/BMR
If we have measured/predicted BMR we can work out EE by assigning a ___ value.
PAL
2 components of energy balance:
- EE
- energy intake
5 traditional methods to assess dietary intake:
- 24 hr dietary recall
- food frequency questionnaire
- diet history
- food record/diary technique
- observed food consumption/chemical/analysis of duplicates
How to assess current dietary intake:
- 24 hour dietary recall
- food record: based on foods and amounts actually consumed by a person on one or more specific days
How to assess habitual dietary intake:
- diet history
- food frequency questionnaire: based on a person’s perceptions of usual intake over a less precisely defined period of time
Pros of 24 hr recall:
- low respondent burden and high compliance
- less chance of selection bias due to low burden
- unlikely to interfere with dietary behaviour
- can be suitable for illiterate subjects (interview)
- standardized protocol can be used (improved data validity)
Cons of 24 hr recall:
- respondent recall depends on short-term memory
- subject must be willing and able to recall diet
- some subjects have little awareness of what they eat
- relies heavily on getting a portion size estimation
- multiple days required to estimate usual intake
Pros of FFQ:
- assesses long-term and usual food intake
- can describe the mean intakes of large groups of subjects
- persons can be ranked according to nutrient intake relative to other members in the group
- low cost
- high response rate and relatively low subject burden
- does not generally affect eating behaviour
- formulation of dietary patterns
Cons of FFQ:
- lacks detail
- finite food list (depends what you ask)
- details of cooking methods
- memory of food use in the past is required
- quantification of portion sizes might be less than accurate
- no information on day to day variation in intake is provided
- not suitable for groups who consume ethnic-specific foods that are not on the food list
Pros of food records:
- Two or more days of recording provide data on within- and between person variation in dietary intakes
- Multiple days of recording may allow persons to be classified according to their usual intakes
- 1- or 2-day records kept intermittently over a year may provide a reasonable estimate of usual intake – seasonal variation?
- Provides data on less frequently eaten foods
- Does not rely on memory
- Portions can be measured or weighed to increase accuracy
Cons of food records:
- Respondents must be literate, highly cooperative, and motivated
- Foods consumed away from home may be less accurately reported/defined
- Usual eating pattern may be influenced by the recording process
- Record keeping increases subject burden
- Accuracy of records may decrease as the number of days increases
- Underreporting - validated phenomenon
Observed food consumption/duplicates involves trained researchers directly ____ a participant’s ____ ____ and ____ to ascertain foods, _____ and _____ consumed.
- observing
- food intake
- behaviours
- brands
- portions
Observed food consumption/duplicates may or may not be within a ____ research environment and it is often preferable if a
participant is not able to identify who the ____ is so they do not alter their ____ ____.
- constrained
- observer
- dietary intake
With observed food consumption/duplicates, subjects ___ and put aside a _____ _____ of all the foods they have eaten, for ____ analysis.
- weigh
- duplicate portion
- chemical
Observed food consumption/duplicates is characterized by having a high degree of ____ but ____ and needs ____ and ____.
- accuracy
- expensive
- time
- effort
Observed food consumption/duplicates are not used in…
clinical or research practice today
Pros of observed food consumption/duplicates:
- objective measure and does not rely on ones’ memory
- can be used to validate another dietary assessment method
- low participant burden (comfort level questionable)
Cons of observed food consumption/duplicates:
- expensive (time required to observe)
- skilled staff required to conduct the interview
- labour and time intensive
- high respondent burden
- participants may alter their usual intake due to observation and could be perceived as an invasive method
People underestimate their true calorie intake by astonishing percentages, ____%, with a range of ____ to ____%.
- 30%
- 10-45%
People also tend to exaggerate intake of foods they think are supposed to be ____ for ____.
good for health
Traditional paper-based dietary assessment methods have limitations due to ____, user ____ and ____, and therefore improved methods are needed to assess important _____ related to diet and health.
- bias
- burden
- cost
- hypotheses
RFPM:
remote food photography method
RFPM estimates ____ and ____ intake in near real time. Estimated by comparing food _____ to _____ of foods with a known ____ ___.
- energy
- nutrient
- images
- images
- portion size
With RFPM, ____ are used to capture images of food ____ and ____ ____ and to send the images to a _____ for food intake estimation. ____ are sent to the smartphones reminding participants to capture food images.
- smartphones
- selection
- plate waste
- server
- prompts
With RFPM, image analysis is performed with a ___ ____ process that relies on ____ ____ and ___ ____. A reference card is used in the pictures to account for the ____ and ____ of the camera.
- semi automatic
- human raters
- computer automation
- viewpoint
- distance
3D calorie counting utilizes ____ scanning and 3D imaging with a ____ to provide estimates of the ____ and ____ profile of food.
- laser
- smartphone
- calories
- nutrition
The inventors of 3D calorie counting are now adapting their technology for consumers and branding it with the name ______.
NutriRay3D
The developers of 3D calorie counting say that their system is ____% accurate.
87-91%
Describe remote sensing devices (iBITE):
watch-like device with micro-electro-mechanical gyroscope to detect and record when an individual has taken a bite of food
Two tests of the accuracy of iBITE device in counting bites found that the method has ___% sensitivity in a controlled meal setting and ___% sensitivity in an uncontrolled meal setting, with one false positive per every ___ bites in both settings.
- 94%
- 86%
- 5
