Healthy Non-Obese Adults (2010-2012)

Study Design:
- Click here for explanation of classification scheme.
Quality Rating:
Research Purpose:

The study objectives were:

  1. Assess the difference in BMR in individuals of similar fatness and BMI, but of different height
  2. Verify the predictive accuracy of FAO/WHO/UNU (1985) equation to estimate BMR.


  • Tall and Short: The selection criteria were the first (<1.65 m) and third(>1.80 m) tertiles of the distribution of the stature of Italian army conscripts
  • WHO/FAO: Used weight and height formula.
Inclusion Criteria:
  1. Young men ages 18-30
  2. Student or staff at the National Institute of Nutrition
  3. Tall or short based on first and third tertiles of the distribution of the stature of Italian army conscripts
  4. Able to give consent.
Exclusion Criteria:
  1. Older men
  2. Height not meeting criteria.
Description of Study Protocol:

Same for all subjects

  • BMR: Measured by Indirect Calorimetry (IC) by open circuit with Douglas bags
  • IC type: Open circuit, IC under standardized conditions
  • Rest before measure: Subjects reclined for 30 min resting prior
  • Measurement length: 10 min; Expired air was collected for 10 min for BMR and 4 min for walking
  • Fasting length: 10-12 hr
  • Exercise condition: Measured during leisurely walking
  • Room temp: Measurements at thermic neutrality
  • No. of measures: Measured in triplicate under standardized conditions
    • Part I: BMR measured at 7:30 am for 10 minutes
    • Part II: Energy cost of walking measured with subject on treadmill at speed of 5 km/h (standardized walking) for 4 minutes, following 4 min run-in period
  • Coefficient of variation: VO2 level not discussed
  • Calibration: Machine regularly calibrated
  • Training of measurer: Not reported
  • Training of subjects to IC process: Not reported
  • Anthropometrics: Height and weight measured using standardized procedures
  • Body fat assessed by underwater weighing; Body fat calculated using Siri’s formula.
Data Collection Summary:
  • RMR was calculated using Weir’s formula
  • FAO/WHO/UNU (1985) equation, using either weight alone or weight and height.

Blinding: Not used.

Description of Actual Data Sample:
  • 46 young men (18-30 y): Selected among students and staff of the National Institute of Nutrition, on the basis of their stature
  • Short (S): N=25; mean stature=1.65±0.03 m)
  • Tall (T): N=21; mean stature=1.87±0.04 m
  • Basal Metabolic Rate: Comparison between observed and predicted—FAO/WHO/UNU.

Tall Group

  • Measured BMR (kcal/d): 1797±177
  • Predicted BMR (kcal/d) from body weight: 1943±126
  • Percentage difference: -7.5%
  • Predicted BMR (kcal/d) from body weight and stature: 1939±126
  • Percentage difference: -7.3 % (p <0.000).

Short Group

  • Measured BMR (kcal/d): 1505±133
  • Predicted BMR (kcal/d) from body weight: 1608±85
  • Percentage difference: -6.4%
  • Predicted BMR (kcal/d) from body weight and stature: 1608±85
  • Percentage difference: –6.4% (p <0.00).
Summary of Results:


  • Data of two groups were compared using unpaired T-test.
  • Analysis of covariance (ANCOVA) was used to adjust BMR for body weight, FFM and stature. BMR and energy cost of walking at 5 km/h were regressed against FFM. Log transformation of the linear regression was used to determine the best model relating BMR, FFM, body weight and stature. Bland & Altman analysis and paired T-test were used to compare the predicted and the measured BMR.
  • Statistical significance was set at P<0.05.

Major results

  • The body fat% and fat-free-mass of the two groups were not statistically different.
  • Basal metabolic rate in kcal/min was 20% higher (P<0.000) in the T group (1.25+0.12 kcal/min) as compared to the S group (1.04+0.09 kcal/min), but when standardized for body weight and FFM, the differences decreased to 12% and 10%, respectively.
  • Adjusting BMR for body weight, FFM, or height by ANCOVA removed all differences between groups.
  • There was no correlation when BMR/FFM was plotted against FFM (r2=0.00) or BMR/weight against weight (r2=0.00).
  • For both groups, the BMR predicted either from weight alone or weight and height using FAO/WHO/UNU equation over-estimated the measured BMR 7% for T and 6% for S (P<0.00). The inclusion of stature did not change the over-estimation.
  • The energy cost of walking was 27% higher in T than in S (P<0.000), but 9% (P<0.000) and 5% lower (P=0.04) when standardized respectively for BW and FFM. The differences disappeared when expressing the energy cost of walking as net cost per kg FFM.
Author Conclusion:
  • The results of this study indicated that the diverse body size that is associated with different stature-even with a similar fat content- influences the BMR as well as the cost of standardized activities (i.e., walking). The normalization of the data on the basis of body weight or FFM does not remove the differences.
  • Tall people have a lower BMR per unit of BW or FFM than short people, and it may be necessary to control for this when comparing energy expenditure of subjects of different stature. Part of the differences observed in the BMR might be accounted for by a different composition of FFM, with a higher proportion of metabolically active visceral organs per unit of FFM in shorter individuals.
  • In addition, the FAO/WHO/UNU equation for predicting BMR significantly overestimates (~6-7%) the measured BMR of young males, but this overestimation does not appear to be related to the effect of stature.
Funding Source:
Government: National Institute of Nutrition
Reviewer Comments:


  • Small sample size; especially when you separated subjects into 2 groups based on stature
  • Self-selection bias-convenience sample; limited generalizability
  • No dietary measurements
  • Although subjects did treadmill testing; physical activity not assessed and no mention of abstaining from physical activity the day prior to IC measurements
  • VO2 level and steady state not discussed; validity of IC.
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? Yes
  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? 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? 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? No
  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