EAL

EE: Respiratory Quotient (RQ) (2014)

Citation:

Study Design:

Class:

- Click here for explanation of classification scheme.

Quality Rating:

Research Purpose:

Hypothesis: lean subjects under normal living conditions (no hospitalization), short-term starvation leads to an increase in serum concentrations of catecholamines and increases in metabolic rate.

Definitions

Steady state: Not defined

Inclusion Criteria:

Understand and give written consent
Healthy adults.

Exclusion Criteria:

Refusal to consent.

Description of Study Protocol:

ANTHROPOMETRIC

Ht measured? Yes
Wt measured? not specified
Fat-free mass measured? No

CLINICAL

Monitored heart rate? No
Body temperature? No
Medications administered? None

Blood samples to measure plasma concentrations of urea, cholesterol, triacylglycerol, insulin, epinephrine, norepinephrine and Beta-hydroxybutyrate.

Urine collected to measure urinary nitrogen.

Resting energy expenditure

IC type: Deltratrac
Equipment of Calibration: see reference Schneeweiss B, Graninger W et al. Energy metabolism in pt w/acute and chronic liver disease. Hepatology. 1990;11:387-393.
Coefficient of variation using std gases: Not available
Rest before measure (state length of time rested if available): 45 min
Measurement length: 45 min
Steady state: not available
Fasting length: First measure, overnight; second measure, 36 h; third measure, 60 hr; fourth measure, 84 hr
Exercise restrictions XX hr prior to test? Yes
Room temp: 26° C
No. of measures within the measurement period: 45
Were some measures eliminated? No
Were a set of measurements averaged? Yes
IF avg, identify length of each measure & no. of measurements? 45 1-min measures
Coefficient of variation in subjects measures? Not available
Training of measurer? Not specified
Subject training of measuring process? Over time; yes with consent.

DIETARY

None: Fasting measures
Individuals allowed fresh water or mineral water without any added sugar.

Intervening factor:

Data Collection Summary:

Outcome(s) and other measures

Measured REE [(VO₂ l/min), VCO₂ (l/min; ml/kg/min), RQ].
Plasma measures of cholesterol, urea, triacylglycerol, glucose, fatty acid, epinephrine, norephinephrine, insulin, and B-hydroxybutyrate,
Independent variables of weight, height, age, BMI.

Blinding used: No

Description of Actual Data Sample:

N=11 healthy, nonsmoking volunteers (4 M; 7 F)
Mean age: 28±4 y
BMI, kg/m²: 22.5±3

Statistical tests

Spearman’s correlation coefficients for each volunteer; the resulting distribution was analyzed to show significant differences of the means using 1-sample t test or Wilcoxon one-sample test. Differences across time, a repeated-measrues analysis of variance (Greenhouse-Geisser); linear contrasts were used for post hoc testing; P <0.05 was considered significant.

Summary of Results:

INDIRECT CALORIMETRY (Mean±SD)

Day 1
Overnight 36 h
Fast
Mean±SD
Day 2
Overnight 36 h
fast
Mean±SD

RQ 0.83±0.05 0.74±0.04ª

RMR, kJ/min
3.97±0.9 4.37±0.9ª

RMR, kcal/min
0.95±.22 1.0±0.22ª

Nonprotein RQ
0.83±0.06 0.73±0.04ª

Weight, kg
64.2±13.5 63.5±13.3 ^a

^a Significantly different from day 1, P<0.05
^b Significantly different from day 2, P<0.05
^c Significantly different from day 3, P<0.05

60 h
Fast
Day 3
Mean±SD 84 h
Fast
Day 4
Mean±SD

RQ
0.72±0.03ª   0.71±0.04ª

RMR, kJ/min
4.53±0.9ª 4.43±0.9ª

RMR, kcal/min
1.1±.22ª   1.1±.22ª

Nonprotein RQ0.70±0.04ª   0.70±0.04ª
0.70±0.04ª   0.70±0.04ª

Weight, kg
62.6±13.2ª   61.5±13.2^a,^{b, c}

^a Significantly different from day 1, P<0.05
^b Significantly different from day 2, P<0.05
^c Significantly different from day 3, P<0.05

Oxygen consumption and RMR increased between days 1 & 2 and remained high until the end. CO₂production rates remained unchanged whereas RQ and non-proteinRQ decreased significantly during the study.

Author Conclusion:

As stated by the author in body of report

“Short term starvation leades to a progressive increase in serum concentrations of norepinephrine, accompanied by an increase in RMR, lipolysis, and ketogenesis in healthy, lean subjects.

“and could be a result of a decline in glucose concentrations . . and may be the primary signal of metabolic changes occurring in early starvation.”

“Previous findings [by Benedict FS in 1915] found a RMR decrease by up to 20% during fasting; however, this reduction in the metabolic rate was found during prolonged starvation only and may have been the result of adaptive mechanisms aimed at conserving body mass.”

Funding Source:

University/Hospital:

University of Vienna

Reviewer Comments:

Strengths

“Measured urine to estimate nonprotein RQ since would deviate from RQ of 0.80.”
Repeated measures design appropriate for study question
Provided analysis techniques for all biological samples.

Generalizability/Weaknesses

“Intentional fasting in healthy adults; unable to generalize toward critically ill or acutely ill adults”
“Study biases include sampling bias of motivated individuals who could fast for 80 hrs may have different characteristics than others.” “Another bias would be the tolerance of a minimum indirect calorimeter measure of 45 minutes.
“Did not provide information on how weight and height were taken.”
An intervening variable not
An important variable affecting RMR measurement accuracy not measured/reported was the frequency of non-steady state measures.”

Quality Criteria Checklist: Primary Research
Relevance Questions
	1.	Would implementing the studied intervention or procedure (if found successful) result in improved outcomes for the patients/clients/population group? (Not Applicable for some epidemiological studies)	Yes
	1.	Would implementing the studied intervention or procedure (if found successful) result in improved outcomes for the patients/clients/population group? (Not Applicable for some epidemiological studies)	Yes
	2.	Did the authors study an outcome (dependent variable) or topic that the patients/clients/population group would care about?	Yes
	2.	Did the authors study an outcome (dependent variable) or topic that the patients/clients/population group would care about?	Yes
	3.	Is the focus of the intervention or procedure (independent variable) or topic of study a common issue of concern to dieteticspractice?	Yes
	3.	Is the focus of the intervention or procedure (independent variable) or topic of study a common issue of concern to dieteticspractice?	Yes
	4.	Is the intervention or procedure feasible? (NA for some epidemiological studies)	Yes
	4.	Is the intervention or procedure feasible? (NA for some epidemiological studies)	Yes

Validity Questions
	1.	Was the research question clearly stated?	Yes
1.	Was the research question clearly stated?		Yes
	1.1.	Was (were) the specific intervention(s) or procedure(s) [independent variable(s)] identified?	N/A
	1.1.	Was (were) the specific intervention(s) or procedure(s) [independent variable(s)] identified?	N/A
	1.2.	Was (were) the outcome(s) [dependent variable(s)] clearly indicated?	N/A
	1.2.	Was (were) the outcome(s) [dependent variable(s)] clearly indicated?	N/A
	1.3.	Were the target population and setting specified?	N/A
	1.3.	Were the target population and setting specified?	N/A
	2.	Was the selection of study subjects/patients free from bias?	No
2.	Was the selection of study subjects/patients free from bias?		No
	2.1.	Were inclusion/exclusion criteria specified (e.g., risk, point in disease progression, diagnostic or prognosis criteria), and with sufficient detail and without omitting criteria critical to the study?	N/A
	2.1.	Were inclusion/exclusion criteria specified (e.g., risk, point in disease progression, diagnostic or prognosis criteria), and with sufficient detail and without omitting criteria critical to the study?	N/A
	2.2.	Were criteria applied equally to all study groups?	N/A
	2.2.	Were criteria applied equally to all study groups?	N/A
	2.3.	Were health, demographics, and other characteristics of subjects described?	N/A
	2.3.	Were health, demographics, and other characteristics of subjects described?	N/A
	2.4.	Were the subjects/patients a representative sample of the relevant population?	N/A
	2.4.	Were the subjects/patients a representative sample of the relevant population?	N/A
	3.	Were study groups comparable?	N/A
3.	Were study groups comparable?		N/A
	3.1.	Was the method of assigning subjects/patients to groups described and unbiased? (Method of randomization identified if RCT)	N/A
	3.1.	Was the method of assigning subjects/patients to groups described and unbiased? (Method of randomization identified if RCT)	N/A
	3.2.	Were distribution of disease status, prognostic factors, and other factors (e.g., demographics) similar across study groups at baseline?	N/A
	3.2.	Were distribution of disease status, prognostic factors, and other factors (e.g., demographics) similar across study groups at baseline?	N/A
	3.3.	Were concurrent controls or comparisons used? (Concurrent preferred over historical control or comparison groups.)	N/A
	3.3.	Were concurrent controls or comparisons used? (Concurrent preferred over historical control or comparison groups.)	N/A
	3.4.	If cohort study or cross-sectional study, were groups comparable on important confounding factors and/or were preexisting differences accounted for by using appropriate adjustments in statistical analysis?	N/A
	3.4.	If cohort study or cross-sectional study, were groups comparable on important confounding factors and/or were preexisting differences accounted for by using appropriate adjustments in statistical analysis?	N/A
	3.5.	If case control study, were potential confounding factors comparable for cases and controls? (If case series or trial with subjects serving as own control, this criterion is not applicable.)	N/A
	3.5.	If case control study, were potential confounding factors comparable for cases and controls? (If case series or trial with subjects serving as own control, this criterion is not applicable.)	N/A
	3.6.	If diagnostic test, was there an independent blind comparison with an appropriate reference standard (e.g., "gold standard")?	N/A
	3.6.	If diagnostic test, was there an independent blind comparison with an appropriate reference standard (e.g., "gold standard")?	N/A
	4.	Was method of handling withdrawals described?	No
4.	Was method of handling withdrawals described?		No
	4.1.	Were follow-up methods described and the same for all groups?	N/A
	4.1.	Were follow-up methods described and the same for all groups?	N/A
	4.2.	Was the number, characteristics of withdrawals (i.e., dropouts, lost to follow up, attrition rate) and/or response rate (cross-sectional studies) described for each group? (Follow up goal for a strong study is 80%.)	N/A
	4.2.	Was the number, characteristics of withdrawals (i.e., dropouts, lost to follow up, attrition rate) and/or response rate (cross-sectional studies) described for each group? (Follow up goal for a strong study is 80%.)	N/A
	4.3.	Were all enrolled subjects/patients (in the original sample) accounted for?	N/A
	4.3.	Were all enrolled subjects/patients (in the original sample) accounted for?	N/A
	4.4.	Were reasons for withdrawals similar across groups?	N/A
	4.4.	Were reasons for withdrawals similar across groups?	N/A
	4.5.	If diagnostic test, was decision to perform reference test not dependent on results of test under study?	N/A
	4.5.	If diagnostic test, was decision to perform reference test not dependent on results of test under study?	N/A
	5.	Was blinding used to prevent introduction of bias?	No
5.	Was blinding used to prevent introduction of bias?		No
	5.1.	In intervention study, were subjects, clinicians/practitioners, and investigators blinded to treatment group, as appropriate?	N/A
	5.1.	In intervention study, were subjects, clinicians/practitioners, and investigators blinded to treatment group, as appropriate?	N/A
	5.2.	Were data collectors blinded for outcomes assessment? (If outcome is measured using an objective test, such as a lab value, this criterion is assumed to be met.)	N/A
	5.2.	Were data collectors blinded for outcomes assessment? (If outcome is measured using an objective test, such as a lab value, this criterion is assumed to be met.)	N/A
	5.3.	In cohort study or cross-sectional study, were measurements of outcomes and risk factors blinded?	N/A
	5.3.	In cohort study or cross-sectional study, were measurements of outcomes and risk factors blinded?	N/A
	5.4.	In case control study, was case definition explicit and case ascertainment not influenced by exposure status?	N/A
	5.4.	In case control study, was case definition explicit and case ascertainment not influenced by exposure status?	N/A
	5.5.	In diagnostic study, were test results blinded to patient history and other test results?	N/A
	5.5.	In diagnostic study, were test results blinded to patient history and other test results?	N/A
	6.	Were intervention/therapeutic regimens/exposure factor or procedure and any comparison(s) described in detail? Were interveningfactors described?	Yes
6.	Were intervention/therapeutic regimens/exposure factor or procedure and any comparison(s) described in detail? Were interveningfactors described?		Yes
	6.1.	In RCT or other intervention trial, were protocols described for all regimens studied?	N/A
	6.1.	In RCT or other intervention trial, were protocols described for all regimens studied?	N/A
	6.2.	In observational study, were interventions, study settings, and clinicians/provider described?	N/A
	6.2.	In observational study, were interventions, study settings, and clinicians/provider described?	N/A
	6.3.	Was the intensity and duration of the intervention or exposure factor sufficient to produce a meaningful effect?	N/A
	6.3.	Was the intensity and duration of the intervention or exposure factor sufficient to produce a meaningful effect?	N/A
	6.4.	Was the amount of exposure and, if relevant, subject/patient compliance measured?	N/A
	6.4.	Was the amount of exposure and, if relevant, subject/patient compliance measured?	N/A
	6.5.	Were co-interventions (e.g., ancillary treatments, other therapies) described?	N/A
	6.5.	Were co-interventions (e.g., ancillary treatments, other therapies) described?	N/A
	6.6.	Were extra or unplanned treatments described?	N/A
	6.6.	Were extra or unplanned treatments described?	N/A
	6.7.	Was the information for 6.4, 6.5, and 6.6 assessed the same way for all groups?	N/A
	6.7.	Was the information for 6.4, 6.5, and 6.6 assessed the same way for all groups?	N/A
	6.8.	In diagnostic study, were details of test administration and replication sufficient?	N/A
	6.8.	In diagnostic study, were details of test administration and replication sufficient?	N/A
	7.	Were outcomes clearly defined and the measurements valid and reliable?	No
7.	Were outcomes clearly defined and the measurements valid and reliable?		No
	7.1.	Were primary and secondary endpoints described and relevant to the question?	N/A
	7.1.	Were primary and secondary endpoints described and relevant to the question?	N/A
	7.2.	Were nutrition measures appropriate to question and outcomes of concern?	N/A
	7.2.	Were nutrition measures appropriate to question and outcomes of concern?	N/A
	7.3.	Was the period of follow-up long enough for important outcome(s) to occur?	N/A
	7.3.	Was the period of follow-up long enough for important outcome(s) to occur?	N/A
	7.4.	Were the observations and measurements based on standard, valid, and reliable data collection instruments/tests/procedures?	N/A
	7.4.	Were the observations and measurements based on standard, valid, and reliable data collection instruments/tests/procedures?	N/A
	7.5.	Was the measurement of effect at an appropriate level of precision?	N/A
	7.5.	Was the measurement of effect at an appropriate level of precision?	N/A
	7.6.	Were other factors accounted for (measured) that could affect outcomes?	N/A
	7.6.	Were other factors accounted for (measured) that could affect outcomes?	N/A
	7.7.	Were the measurements conducted consistently across groups?	N/A
	7.7.	Were the measurements conducted consistently across groups?	N/A
	8.	Was the statistical analysis appropriate for the study design and type of outcome indicators?	No
8.	Was the statistical analysis appropriate for the study design and type of outcome indicators?		No
	8.1.	Were statistical analyses adequately described and the results reported appropriately?	N/A
	8.1.	Were statistical analyses adequately described and the results reported appropriately?	N/A
	8.2.	Were correct statistical tests used and assumptions of test not violated?	N/A
	8.2.	Were correct statistical tests used and assumptions of test not violated?	N/A
	8.3.	Were statistics reported with levels of significance and/or confidence intervals?	N/A
	8.3.	Were statistics reported with levels of significance and/or confidence intervals?	N/A
	8.4.	Was "intent to treat" analysis of outcomes done (and as appropriate, was there an analysis of outcomes for those maximally exposed or a dose-response analysis)?	N/A
	8.4.	Was "intent to treat" analysis of outcomes done (and as appropriate, was there an analysis of outcomes for those maximally exposed or a dose-response analysis)?	N/A
	8.5.	Were adequate adjustments made for effects of confounding factors that might have affected the outcomes (e.g., multivariate analyses)?	N/A
	8.5.	Were adequate adjustments made for effects of confounding factors that might have affected the outcomes (e.g., multivariate analyses)?	N/A
	8.6.	Was clinical significance as well as statistical significance reported?	N/A
	8.6.	Was clinical significance as well as statistical significance reported?	N/A
	8.7.	If negative findings, was a power calculation reported to address type 2 error?	N/A
	8.7.	If negative findings, was a power calculation reported to address type 2 error?	N/A
	9.	Are conclusions supported by results with biases and limitations taken into consideration?	Yes
9.	Are conclusions supported by results with biases and limitations taken into consideration?		Yes
	9.1.	Is there a discussion of findings?	N/A
	9.1.	Is there a discussion of findings?	N/A
	9.2.	Are biases and study limitations identified and discussed?	N/A
	9.2.	Are biases and study limitations identified and discussed?	N/A
	10.	Is bias due to study's funding or sponsorship unlikely?	Yes
10.	Is bias due to study's funding or sponsorship unlikely?		Yes
	10.1.	Were sources of funding and investigators' affiliations described?	N/A
	10.1.	Were sources of funding and investigators' affiliations described?	N/A
	10.2.	Was the study free from apparent conflict of interest?	N/A
	10.2.	Was the study free from apparent conflict of interest?	N/A

	Day 1 Overnight 36 h Fast Mean±SD	Day 2 Overnight 36 h fast Mean±SD
RQ	0.83±0.05	0.74±0.04ª
RMR, kJ/min	3.97±0.9	4.37±0.9ª
RMR, kcal/min	0.95±.22	1.0±0.22ª
Nonprotein RQ	0.83±0.06	0.73±0.04ª
Weight, kg	64.2±13.5	63.5±13.3 ^a

	60 h Fast Day 3 Mean±SD	84 h Fast Day 4 Mean±SD
RQ	0.72±0.03ª	0.71±0.04ª
RMR, kJ/min	4.53±0.9ª	4.43±0.9ª
RMR, kcal/min	1.1±.22ª	1.1±.22ª
Nonprotein RQ0.70±0.04ª 0.70±0.04ª	0.70±0.04ª	0.70±0.04ª
Weight, kg	62.6±13.2ª	61.5±13.2^a,^{b, c}