EE: Thermic Effect of Food (2014)


Blond E, Maitrepierre C, Normand S, Sothier M, Roth H, Goudable J, Laville. A new indirect calorimeter is accurate and reliable for measuring basal energy expenditure, thermic effect of food and substrate oxidation in obese and healthy subjects. e-SPEN, the European e-Journal of Clinical Nutrition and Metabolism. 2010;6:e7–e15.

Study Design:
Diagnostic, Validity or Reliability Study
C - Click here for explanation of classification scheme.
Quality Rating:
Neutral NEUTRAL: See Quality Criteria Checklist below.
Research Purpose:

To validate accuracy and reliability of the QUARK RMR, an indirect calorimeter vs. the DELTATRAC II, a well-established reference system which is no longer available, in resting and post-prandial conditions.

Inclusion Criteria:
  • Provided written informed consent
  • Low to moderate physical activity level confirmed by Baecke's questionnaire.
Exclusion Criteria:
  • Volunteers were excluded if they performed intensive activity
  • Smokers
  • Claustrophobic
  • Pregnant or breastfeeding women
  • Acute infection
  • Chronic inflammatory disease or taking medication that could interfere with metabolic rate.
Description of Study Protocol:


Volunteers were recruited for this study.


Validity and reliability study.

Blinding Used

Implied with measurements.


  • A crossover, randomized study was performed for two consecutive days
  • Resting metabolic rate was measured for three 45-minute periods using alternating calorimeters
  • Thermic effect of food (TEF) and substrate oxidation were assessed for three hours with each calorimeter and 15 minutes after meal ingestion.

Statistical Analysis

  • Sample size was defined by a power analysis of 2x2 crossover design to test equivalence using maximal allowable differences that still result in equivalence and the standard deviation (SD) of the individual differences defined after previous measures of RMR with DeltaTrac II for two consecutive days
  • STATA II software was used for statistical analysis. All data are reported as means ± SD.
  • Comparison of population characteristics on the two test days was performed using a Student's paired T-test at alpha equals 0.05
  • Statistical reliability of mean VCO2, VO2, RMR, RQ and substrate oxidation at rest was determined by the correlation method using Pearson's correlation test
  • Accuracy and agreement of these parameters were determined by the Bland and Altman plot to assess the limits of agreement and were tested by a Pitman test
  • Longitudinal analysis of post-prandial metabolic rate variation between calorimeters was performed using a generalized estimating equations (GEE) model which took into account time, the type of calorimeters, sex, BMI class and randomization arm
  • TEF obtained with the two calorimeters was also compared using a GEE model as for substrate oxidation
  • For all statistical analysis, the 0.05 level of significance was used.
Data Collection Summary:

Timing of Measurements

A crossover, randomized study was performed for two consecutive days. During the basal period subjects had an overnight fast that was controlled on arrival at the center by capillary glycemia and anthropometric measurements.

 Dependent Variables

  • Resting metabolic rate was measured for three 45-minute periods using alternating calorimeters after a 30-minute rest period
  • An average of VO2 and VCO2 values were taken from subsequent 40-minute steady state readings and was used to calculate RMR with the two calorimeters
  • During basal and post-prandial periods, readings from the first five minutes were discarded to keep only values reflecting steady state software of both calorimeters
  • RMR was determined with the WEIR equation, respiratory quotient was assessed as the VCO2/VO2 ratio
  • Substrate oxidation during the post-prandial period was assessed using Ferrannini's equations. Variation of substrate oxidation was calculated by subtracting mean substrate oxidation obtained during the basal period from substrate oxidation in the post-prandial period.

Independent Variables

  • Thermic effect of food (TEF) and substrate oxidation were assessed for three hours with each calorimeter and 15 minutes after meal ingestion:
    • Quark RMR
    • DeltaTrac.
  • Food intake was calibrated after an interview with a dietitian, standardized evening meals were calibrated and an identical standard meal was served during the two consecutive test days
  • After the basal period, subjects consumed a 687kcal solid meal composed of 100g minced steak, 200g cooked pasta, 1 yogurt, 100g cottage cheese, 10g sugar, 67.8g carbohydrates to monitor substrate oxidation and TEF
  • During the post-prandial period, measurements started 15 minutes after complete lunch consumption and continued for three hours with the same calorimeter.

Control Variables

  • Environmental conditions were also standardized, rooms were air-conditioned and temperatures and humidity were controlled regularly to maintain the same condition during the two consecutive test days
  • Before each experiment, both calorimeters were warmed up following the manufacturer's instructions, calibrated with a gas of known and certified CO2 and O2 composition.
Description of Actual Data Sample:
  • Initial N: 34 enrolled
  • Attrition (final N): 30 (five men and five women in the normal weight category, five men and five women in the overweight category and five men and five women in the obese category)
  • Age:
    • Mean age in the normal weight category (182) was 26.8 years for men and 37.4 years for women
    • Mean age in the overweight category (252) was 29.2 years for men and 30.4 years for women
    • Mean age in the obese category is 39.4 years for men and 35.0 years for women
  • Anthropometrics: Subjects served as own control in crossover design:
    • Mean BMI (kg/m2) in the normal category is 22.1 for men and 22.8 for women
    • Mean BMI (kg/m2) in the overweight category is 28.6 for men and 27.8 for women
    • Mean BMI (kg/m2) in the obese category is 31.1 for men and 32.6 for women
  • Location: France.


Summary of Results:

Key Findings

  • Means at rest of VO2, VCO2 RMR and substrate oxidation were not significantly different with both devices
  • The variability of VO2, VCO2 and RMR measurements at rest for each device on two consecutive days was similar to that measured with QUARK RMR and DELTATRAC II the same day, under standardized conditions
  • Longitudinal analysis of TEF and post-prandial substrate oxidation was equivalent with the two devices.
Author Conclusion:

The results from this study highlight the validity of the Quark RMR calorimeter for measuring basal and post-prandial EE and substrate oxidation in normal and overweight subjects.

Funding Source:
Cosmed Sarl, Rome, Italy
Reviewer Comments:

Small numbers of subjects in weight groups.

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
  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
  4. Is the intervention or procedure feasible? (NA for some epidemiological studies) Yes
Validity Questions
1. Was the research question clearly stated? Yes
  1.1. Was (were) the specific intervention(s) or procedure(s) [independent variable(s)] identified? Yes
  1.2. Was (were) the outcome(s) [dependent variable(s)] clearly indicated? Yes
  1.3. Were the target population and setting specified? Yes
2. Was the selection of study subjects/patients free from bias? ???
  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? ???
  2.2. Were criteria applied equally to all study groups? Yes
  2.3. Were health, demographics, and other characteristics of subjects described? Yes
  2.4. Were the subjects/patients a representative sample of the relevant population? ???
3. Were study groups comparable? Yes
  3.1. Was the method of assigning subjects/patients to groups described and unbiased? (Method of randomization identified if RCT) Yes
  3.2. Were distribution of disease status, prognostic factors, and other factors (e.g., demographics) similar across study groups at baseline? Yes
  3.3. Were concurrent controls or comparisons used? (Concurrent preferred over historical control or comparison groups.) Yes
  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
  3.6. 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? Yes
  4.1. Were follow-up methods described and the same for all groups? Yes
  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%.) Yes
  4.3. Were all enrolled subjects/patients (in the original sample) accounted for? Yes
  4.4. Were reasons for withdrawals similar across groups? Yes
  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? Yes
  5.1. In intervention study, were subjects, clinicians/practitioners, and investigators blinded to treatment group, as appropriate? No
  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.) Yes
  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
  5.5. 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
  6.1. In RCT or other intervention trial, were protocols described for all regimens studied? Yes
  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? Yes
  6.4. Was the amount of exposure and, if relevant, subject/patient compliance measured? Yes
  6.5. Were co-interventions (e.g., ancillary treatments, other therapies) described? Yes
  6.6. Were extra or unplanned treatments described? Yes
  6.7. Was the information for 6.4, 6.5, and 6.6 assessed the same way for all groups? Yes
  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? Yes
  7.1. Were primary and secondary endpoints described and relevant to the question? Yes
  7.2. Were nutrition measures appropriate to question and outcomes of concern? Yes
  7.3. Was the period of follow-up long enough for important outcome(s) to occur? Yes
  7.4. Were the observations and measurements based on standard, valid, and reliable data collection instruments/tests/procedures? Yes
  7.5. Was the measurement of effect at an appropriate level of precision? Yes
  7.6. Were other factors accounted for (measured) that could affect outcomes? Yes
  7.7. Were the measurements conducted consistently across groups? Yes
8. Was the statistical analysis appropriate for the study design and type of outcome indicators? Yes
  8.1. Were statistical analyses adequately described and the results reported appropriately? Yes
  8.2. Were correct statistical tests used and assumptions of test not violated? Yes
  8.3. Were statistics reported with levels of significance and/or confidence intervals? Yes
  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)? Yes
  8.6. Was clinical significance as well as statistical significance reported? Yes
  8.7. If negative findings, was a power calculation reported to address type 2 error? Yes
9. Are conclusions supported by results with biases and limitations taken into consideration? Yes
  9.1. Is there a discussion of findings? Yes
  9.2. Are biases and study limitations identified and discussed? Yes
10. Is bias due to study's funding or sponsorship unlikely? Yes
  10.1. Were sources of funding and investigators' affiliations described? Yes
  10.2. Was the study free from apparent conflict of interest? Yes