EE: Application of RQ (2005)


Johnstone AM, Faber P, Gibney ER, Elia M, Horgan G, Golden BE, Stubbs RJ. Effect of an acute fast on energy compensation and feeding behaviour in lean men and women. International J Obes. 2002;26:1623-1628.

Study Design:
Repeat measures crossover
C - Click here for explanation of classification scheme.
Quality Rating:
Neutral NEUTRAL: See Quality Criteria Checklist below.
Research Purpose:
  1. To examine the extent to which healthy male and female subjects undergoing a short-term total fast (36-hours)
  2. To examine how subjects compensate by altering their energy intake and macronutrient selection


  • Steady state:
Inclusion Criteria:
  1. Understand and give written consent
  2. Normal weight (i.e., BMI 20-25)
  3. Not consuming any specialized diet
  4. Not taking medication (except oral contraceptives in women)
  5. Medical suitability for fasting as per medical examination
Exclusion Criteria:
  1. Refusal to consent
  2. Not meeting inclusion criteria
  3. Diseases in subjects that were excluded:
  4. Medications excluded:
Description of Study Protocol:


  • Ht measured? Yes
  • Wt measured? Yes
  • Fat-free mass measured?


  • Monitored heart rate?
  • Body temperature?
  • Medications administered?

Resting energy expenditure

  • IC type: ventilated hood
  • Equipment of Calibration: not specified
  • Coefficient of variation using std gases: No
  • Rest before measure (state length of time rested if available): Measured first thing in a.m.
  • Measurement length: 30-40 min
  • Steady state: “subjects required to lie still but not fall asleep”
  • Fasting length: overnight, 36 hr
  • Exercise restrictions XX hr prior to test? Yes
  • Room temp: thermoneutral
  • No. of measures within the measurement period: 2 –overnight fast and after 36 hr fast
  • Were some measures eliminated? Not specified
  • Were a set of measurements averaged?
  • Coefficient of variation in subjects measures? Not specified
  • Training of measurer? Not specified
  • Subject training of measuring process? Yes


  • Dietary information not abstracted due to only appraising fasting RQ

Intervening factor:

Data Collection Summary:

Outcome(s) and other measures

  1. Measured REE [(VO2 l/min), VCO2 (l/min; ml/kg/min), RQ, ventilation (l/min)].
  2. Independent variables of weight, height, age, BMI,and fat-free mass, fat mass
  3. Feeding behavior with use of a Dutch Eating Behavior survey

Blinding used: No for IC; however, blinded to outcome variable of feeding behavior although was inherently obvious

Description of Actual Data Sample:
  • N=12 lean men and 12 lean women
  • Mean age, y (men): 27.4±9.7 (SD)
  • Mean age, y (women): 20.6±2.9 (SD)

Statistical tests

ANOVA by calculating a mean rating for each 24 h period with diet, gender and time treatment factors and subject as a blocking factor. Body weight change was analyzed by a one-sampel t-test to establish whether wt loss was significantly different from zero.

Summary of Results:


Men Mean±SD

Wt, kg 


Ht, cm 






Wt, kg 


Ht, cm 





After an overnight fast and 36 hour fast, on average RQ decreased significantly (P<0.05) from 0.81 (±SD 0.04) to 0.73(±0.05)

[Analyst note: Assuming normality, 98% of 24 individuals would have an RQ fall within the range of 0.73- 0.89 after an overnight fast and from 0.63-0.83 after a 36 hour fast].

Author Conclusion:

As stated by the author in body of report

In our study, data suggest that subjects cannot or are not inclined to consume enough food to restore 24 h energy requirements subsequent to an acute 36 h total fast. In response to the energy deficit, subjects altered feeding behaviour only at breakfast time, selecting a high-fat meal. Thereafter, feeding behaviour and motivation to eat were unaffected, which suggests that post-absorptive feedback over this time period is very weak.

“This study was conducted in mildly restrained, lean indvidiuals and it may be that obese or more restrainedindivdiuals may respond differently to a short-term fast.”

“Considerable limitations—is used a small number of non-randomly selected, mildly restrained, lean, young men and women. Motivation to eat was only measured on the fasting treatment, the duration of the fast was very short. Data may not be generalizable to other subject groups such as children, older adults, the obese or highly restrained subjects.”
Funding Source:
Government: Scottish Executive Environment and Rural Affairs Department
Slimming World (UK)
Reviewer Comments:


  • “ . . . . .”


  • For generalizability groups see discussion above”
  • Important variables on REE measurement accuracy include machine calibration.”
  • Did not provide individual RQ errors.
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? 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
2. Was the selection of study subjects/patients free from bias? Yes
  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
  2.3. 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
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
  3.2. 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
  3.4. 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? No
  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
  4.3. Were all enrolled subjects/patients (in the original sample) accounted for? N/A
  4.4. Were reasons for withdrawals similar across groups? N/A
  4.5. 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? 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
  5.4. 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? 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
  6.4. 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
  6.6. 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
  6.8. 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
  7.1. 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
  7.3. 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
  7.5. 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
  7.7. Were the measurements conducted consistently across groups? N/A
8. Was the statistical analysis appropriate for the study design and type of outcome indicators? Yes
  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
  8.3. 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
  8.5. 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
  8.7. 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
  9.1. Is there a discussion of findings? 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
  10.1. Were sources of funding and investigators' affiliations described? N/A
  10.2. Was the study free from apparent conflict of interest? N/A