• Increase Font Size
  • Decrease Font Size
  • View as PDF

Healthy Non-Obese Adults (2010-2012)

Citation:
 
Study Design:
Class:
- Click here for explanation of classification scheme.
Quality Rating:
Research Purpose:
  • To explore the relationship between measured RMR and predicted RMR using the Harris-Benedict equation in healthy volunteers and in a data set from the literature
  • To compare measured RMR with six more recent equations
  • To determine if between-person variation is randomly distributed.
Inclusion Criteria:
  • Healthy normal weight volunteers
  • Sedentary lifestyle (<1.5 hours of aerobic exercise per week).
Exclusion Criteria:

None specified

Description of Study Protocol:

Recruitment

Procedures not specified

Design

Cross-sectional study

Blinding used

Not used

Intervention

Not applicable

Statistical Analysis

  • Descriptive statistics (mean±SD and mean±SD)
  • Percentage overestimation or underestimation of energy expenditure by each predictive equation.
Data Collection Summary:

Timing of Measurements

One measurement

Dependent variables

  • Predictive value of equations: The number of cases where the measured RMR was within 10% of the value predicted by using each of the formulas
    • Height and weight: Procedures for obtaining not specified.

Independent variables

  • Measured resting metabolic rate (RMR): (Weir equation)
    • IC type: Continuous open circuit with continuous measurements of CO2 and O2 concentrations in inspired and expired air diluted in a constant air flow, generated by the analyzer
    • Rest before measure: 30 minutes
    • Measurement length: 30 minutes with the last 20 minutes being recorded
    • Fasting length: 12 hours
    • Exercise conditioning 24 prior to test? Sedentary lifestyle (<1.5 hour of aerobic exercise per week
    • Room temp: Not reported
    • Number of measures were they repeated? Two measures
    • Coefficient of variation? Coughing, yawning and so on were marked and the value excluded from the calculations
    • Equipment calibration:  Yes, O2 precision was 99%; CO2 was 2-4%
    • Training of measurer? Not reported
    • Subject training of measuring process? Subjects underwent a training session
    • Calculations of energy expenditure: Made from O2 and VCO2 during the last 20 minutes of each 30 minutes measuring period using the Weir equation and from UN elimination over a six-hour period on the day of the measurement
    • Steady state: None defined
    • Monitored heart rate? No
    • Body temperature? No.

Control variables

  • Body composition was estimated using skinfold measurements at four sites triceps, biceps, suprailiac and subscapular 
    • Body density calculated using formula of Durnin & Womersely
    • Percent body fat using Siri equation
    • LBM was calculated by subtracting the obtained fat mass from the total body mass.
Description of Actual Data Sample:
  • Initial N: Not given
  • Attrition (final N): N=67 subjects (39 males, 28 females)
  • Age: Mean age: 25±5 years
  • Ethnicity: Not reported
  • Other relevant demographics: None had a personal or familial history of obesity or diabetes. None of the women used oral contraceptives.
  • Anthropometrics:

 

  Men Women
  ±SD ±SD
Weight (kg) 71.6±7.8 57.7±6.6
Height (cm) 1.75±60.05 1.64±0.06
BMI 23.3±2.3 21.6±2.2
LBM (kg) 58.7±4.7 41.9±3.1
HB (kJ per 24 hours) 7,323±506 5,848±305
RMR (kJ per 24 hours) 6,780±531 5,070±485

 

  • Location: Montreal, Quebec, Canada.
Summary of Results:
  • The mean overestimation of the measured by the RMR by the HB equations was 11.7%.  When measured values were divided in quartiles, the overestimations were 20.6%, 11.5%, 9.5% and 4.0% for the lowest to the highest quartile.
  • The mean overestimation by Owen et al was 7.4% and by quartile was 19.8%, 8.1%, 5.9% and -3.5% for the lowest to the highest 
  • The equations of Owen et al predicted measured values within a 10% difference in more than 80% of the subjects
  • The WHO predicted the measured RMR in 100% of the cases; with the other four equations (HB, Bernstein, James, Roberson & Reid, Mifflin) [NOTE: Author states four but lists five others], the percent of predicted values within 10% of the measured values varied between 28% to 74%. 
  • In most of the equations, predicted values for women were less accurate than for men.
Author Men, Percent Women, Percent
Mifflin et al 62±102 39±137
Owen et al 95±69 82±9
HB 73±116 31±91
WHO 100±77 100±46
Bernstein et al 28±107 64±43
James 56±79 50±80
Robertson and Reid 74±101 36±74

 

Values are percents ±SE

 

Author Conclusion:

As stated by the author in body of report:

“Our study confirms the findings of an overestimation of RMR by the Harris and Benedict equations and show that an inverse relationship exists between the difference from the HB equations and the absolute value of RMR. This results in a larger error when estimating resting energy expenditure in women and in people of small body size.”

“Our results show that the overestimation of RMR by the Harris and Benedict equations is not a homogenous finding but that a high variation between individuals can be observed; the overestimation is higher in persons with a low RMR when compared with individuals than with a higher RMR and that the same relationship between RMR and HB values could be observed in the population studied by Owen et al. This shows an inverse relationship between overestimation of RMR by HB and the absolute value of RMR.

“An explanation for this is that the relationship between RMR and the FFM is not linear but that energy expenditure increases faster with increasing LBM in the lower range than in the upper range.”

“One limitation of our study is [none listed]”

Funding Source:
University/Hospital: University of Montreal Medical School, Medical Research Centre of Hotel-dieu Hospital (Canada)
Reviewer Comments:

Strengths

  • Body composition measured (skinfolds)
  • Had subject training of the measurement process
  • Calibrated equipment.

Generalizability/Weaknesses 

  • ”Limited generalizability as sampling method to obtain subjects limited”
  • Did not report if ethnic groups were included, recent weight change and physical activity within 24 hours of measurement; did not account for gender differences
  • Unclear how body composition data was used
  • Room temperature when IC measurement taken and training of measurer not reported; no definition of steady state-although eliminated the first 10 minutes of measurements
  • Author reports SE percentages which are confusing.
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? ???
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? No
  2.2. Were criteria applied equally to all study groups? N/A
  2.3. Were health, demographics, and other characteristics of subjects described? ???
  2.4. Were the subjects/patients a representative sample of the relevant population? ???
3. Were study groups comparable? No
  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? Yes
  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? No
  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.) No
  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%.) ???
  4.3. Were all enrolled subjects/patients (in the original sample) accounted for? No
  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? No
  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? Yes
  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? 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? 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? No
  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? No
  8.1. Were statistical analyses adequately described and the results reported appropriately? No
  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? No
  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)? No
  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? N/A
9. Are conclusions supported by results with biases and limitations taken into consideration? ???
  9.1. Is there a discussion of findings? Yes
  9.2. Are biases and study limitations identified and discussed? No
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