EAL

Healthy Non-Obese Adults (2010-2012)

Citation:

Study Design:

Class:

- Click here for explanation of classification scheme.

Quality Rating:

Research Purpose:

Develop better predictive equations for BMR in healthy Chinese adults
Evaluate factors that may influence BMR.

Definitions

Steady state: VO₂and CO₂measurements obtained every 30-secs until equilibrium achieved for at least 5 to 6 consecutive minutes
Harris-Benedict equation: Cited 1918 study
Ideal body weight: Cited Huang 1992 for Chinese persons
Body fat: Siri’s equation, 1961
Body Surface Area (BSA) equation: used formula derived from Dubois and Dubois
Body Cell Mass (BCM) equation: Used Moore equation
Fat-free mass (FFM): Body weight (1-%body fat).

Inclusion Criteria:

Understand and give written consent
Healthy
Normal weight for Chinese persons (based on equations derived by Huang et al for Chinese persons).

Exclusion Criteria:

Refusal to consent
Hx of current illnesses
Recent weight loss
Endocrine disorders
Pharmacologic therapy
Hormonal treatment
Extremely underweight (<80% IBW) or obese (120% IBW).

Description of Study Protocol:

Recruitment

Procedures not described

Design

Cross-sectional study

Subjects stratified on basis of gender and age (20-29, 30-39, 40-49, 50-59, 60+ years)

Blinding used

Not applicable

Intervention

Not applicable

Statistical Analysis

Student's T-test used to assess differences between men and women
Pearson correlation coefficients and linear regression analyses used to evaluate relationships between measured BMR and age, weight, height, percentage ideal body weight, percent body fat, fat-free mass, body surface area and body cell mass results expressed as mean±standard deviation (SD)
Cross-validation study: Sample was randomly divided into two groups for development and cross-validation of predictive equations; there were no differences in body composition parameters between each sample.

Data Collection Summary:

Timing of measurements

One measurement time

Dependent variables

Measured BMR: Indirect calorimetry [(VO₂, liters per minute), VCO₂ (liters per minute; ml/kg per minute)].
- C type: Metabolic cart with a canopy system
- Rest before measure: “Relaxed supine position”
- Fasting length: 12 hours; Measured between 8-10 a.m.
- Exercise conditioning 24 prior to test: Refrain 12 hours before test
- Smoking: Refrain one hour before test
- Room temp: Not reported
- No. of measures were they repeated? O₂ and CO₂ taken at 30 second intervals until a steady-state was achieved and maintained for at least five to six consecutive minutes
- Steady state: VO₂ and CO₂ measurements obtained every 30-seconds until equilibrium achieved for at least five to six consecutive minutes
- Coefficient of variation? None reported
- Equipment of Calibration: None reported
- Training of measurer? Dietitians trained to use a standardized protocol
- Subject training of measuring process? None reported
- Sleep at the facility: Not reported
- Monitored heart rate? None reported
- Body temperature? None reported.

Independent variables

Predicted REE using HB, Mifflin, Owen (men), Owen(women), Kleiber, Cunningham
- Harris-Benedict equation: Cited 1918 study
Height: Method not reported
Weight: Method not reported
Body mass index (BMI: kg/m²
Ideal body weight: based on Huang, 1992 for Chinese persons
Body composition (body fat and fat free mass): sum of skinfolds (biceps, triceps, subscapular, suprailiac) and bioelectrical impednace analysis, resistance and reactance
- Body fat: Siri’s equation, 1961
- Fat free mass (FFM): body weight (1% body fat)
Body Surface Area (BSA) equation: Formula derived from Dubois and Dubois
Body Cell Mass (BCM) equation: Moore equations for males and females.

Control variables

Age and gender: Sample stratified

Description of Actual Data Sample:

Initial N: Not given
Attrition (final N): N=223 Chinese adults (N=102 males; N=121 females)
Age: Mean age: 43.8±14.3 years; range: 20-78 years
Ethnicity: Chinese
Anthropometrics:

	Men N=102 Mean±SD	Women N=121 Mean ±SD
Weight, kg	63.5±7.6	52.9±5.0*
Height, cm	167.5±5.3	157±4.0*
BMI	22.6±2.4	21.5±2.2
BFS, percent	15.2±4.4	28.6±4.2*
BFB, percent	15.7±3.7	27.6±3.7*#
FFMS, kg	53.7±5.2	37.6±2.7*
FFMB, kg	53.4±6.1	38.2±2.8*
BCM, kg	25.8±3.2	17.9±1.3*
BSA, m²	1.72±0.11	1.51±0.08*
%IBW	103.7±10.9	101.3±9.8

BFS: Body fat measured by BIA; BFB- Body fat measured by bioelectrical impedance analysis; FFMS-fat-free mass measured by skinfold thicknesses; FFMB- fat-free mass measured by BIA, BCM-body cell mass; BSA- body surface area
* Significantly different from men at P=0.0001
# Significantly different from BFS at P=0.02.
Location: Taipei, Taiwan.

Summary of Results:

Pearson Correlation Coefficients between:

BMR and weight: 0.77
BMR and height: 0.73
BMR and age: -0.25
BMR and percent IBW: 0.33
BMR and BFS: -027
BMR and BFB: -0.34
BMR and FFMS: 0.84
BMR and FFMB: 0.86
BMR and BSA: 0.80
BMR and BCM: 0.89.

BMR best correlated with body cell mass (BCM) and BCM correlated best with fat-free mass by BIA (R=0.94). There was a negative correlation between BCM and age (-0.28).

BMR adjusted for body composition and body surface area

	Male N=102	Female N=121*
BMR/weight kcal/kg	22±2	20±2*
BMR/FFM kcal/kg	26±2	28±3*
BMR/BCM kcal/kg	54±4	59±5*
BMR/BSA kcal/m²	799±69	700±76

* P=0.0001

Clinical: Resting energy expenditure

	Male Mean±SD	Female Mean±SD
VO₂ (mL/min)	197±23	153±16*
VCO₂ (mL/min)	175±21	134±16*
RQ	0.89±0.05	0.88±0.05

P=0.0001

Differences between measured and predicted RMR in males and females comparison measured BMR and estimate BMR (i.e., total sample) by different predictive equations

[Taken from Liu HY, Lu YF, Chen WJ. Validity of predictive equations for the calculation of basal metabolic rate in healthy Chinese adults. Chinese Nutr Soc. 1994; 19 (2): 141-150.]

	Kcal/day (±SD)	(Percent±SD)
Males, N=102; Females, N=121
Measured	1,202±207
Harris & Benedict	1,3?5±170	(114±11%)
Mifflin	1,288±198	(108±9%)
Owen	1,336±185	(112±11%)

Differences between measured and predicted RMR in males and females

	Kcal per day (±SD)	(Percent±SD)
Males, N=102
Measured	1,372±175
Harris & Benedict	1,481±167	(108±8%)
Mifflin	1,470±131	(108±8%)
Owen	1,527±77	(112±11%)
Females, N=121
Measured	1,058±113
Harris & Benedict	1,258±70	(119±11%)
Mifflin	1,135±82	(108±10%)
Owen	1,176±36	(112±11%)

Developing predictive equations

The men and women in the two samples (validation and cross-validation) were comparable in age, anthropometric measurements (height and weight), body composition (including percent body fat, fat-free mass and body cell mass) and body surface area.

The mean difference, r and P-value for paired T-test results between predicted BMR (X-var) and measured BMR (Y-var) using cross-validation sample (N=104):

	Mean difference (kcal per day)	r	P-value
HB (Uses weight, height, age, sex variables)	158±111	0.84	0.0001
Cunningham (Uses FFM variable)	278±111	0.85	0.0001
Owen (Uses weight, sex variables)	137±114	0.84	0.0001
Mifflin (Uses weight, height, age, sex)	92±97	0.88	0.0001
Kleiber	262±142	0.73	0.0001
Mifflin	117	0.44	0.0001

All of the available predictive equations overestimated BMR in healthy Chinese adults (P=0.0001)

The mean difference, r and P-value for paired T-test results between predicted BMR (X-var) and measured BMR (Y-var) in cross-validation sample (N=104)

	Mean difference (kcal per day)	r	P-value
C3 (Uses FFM and age variables)	7±96	0.89	0.4497
C5 (Uses FFM, age and weight variables)	6±100	0.88	0.5630
C6 (Uses weight, age, sex variables)	5±98	0.88	0.6294
C7 (Uses weight, height, age, sex)	7±101	0.87	0.5078
C8	7±101	0.87	0.5078

No significant differences were observed between measured BMR and predicted values estimated by the nine equations developed in this study

[NOTE: The four equations above are discussed due to availability of obtaining the factors needed.]

The BMR was estimated in 10 randomly selected subjects from the cross-validation study using Mifflin et al equation and equation 8
Significant differences were observed between BMR estimated by Mifflin and measured BMR (P=0.0001). No significant differences were observed between measured BMR and BMR estimated by equation 8.

Author Conclusion:

As stated by the author in body of report:

In our study, women had a lower metabolic rate than men because of a relatively smaller amount of body cell mass; the result of smaller skeletal muscle mass in tandem with greater fat mass.
The major difference between men and women was the difference in amount of skeletal muscle mass
Previous findings suggest resting energy expenditure correlated most highly with fat-free mass, which correlated highly with weight and height. Our results agree that accurate determination of height and weight, not calorimetry or assessment of body composition are needed to provide a base for estimating daily energy expenditure of individual mean and women.
Fat-free mass was the best single predictor of BMR and could explain 75% of the variance observed among people... the same r² value was obtained when body weight and body height were used to substitute fat-free mass for predicting BMR. The use of four variables-body weight, body height, age and sex resulted in an r² value of 0.81. 81% of the variance in BMR among persons was accounted for by the covariates of weight, height, age and sex.
A significant degree of overestimation was still observed in predicting BMR in Chinese adults using the Mifflin et al equations (P=0.0001)
We do not know if predictive equations overestimated BMR for Chinese adults is the result of ethnic differences or other factors such as climate and lifestyle
We recommend these [our] equations for clinical use in healthy Chinese adults who are within normal limits for body weight.

Funding Source:

Government:

Dept. of Health-Republic of China

Reviewer Comments:

Strengths

Selected an important ethnic group within a healthy population.

Generalizability/Weaknesses

Large study population represented and stratified by age
Cross-validated equations on separate stratified sample
Study weaknesses include:
- No subject training prior to measurement; did not sleep over at facility where measurement being taken-hence definition of “BMR” is most likely “Resting metabolic rate”
- Room temperature not reported
- Sample represents Chinese adults living in Taipei, Taiwan, Republic of China; Hence, considering lifestyle differences-limited generalizability to US-residing Chinese population.

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?	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
	1.2.	Was (were) the outcome(s) [dependent variable(s)] clearly indicated?	Yes
	1.3.	Were the target population and setting specified?	Yes
	1.3.	Were the target population and setting specified?	Yes
	2.	Was the selection of study subjects/patients free from bias?	???
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?	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?	Yes
	2.2.	Were criteria applied equally to all study groups?	Yes
	2.2.	Were criteria applied equally to all study groups?	Yes
	2.3.	Were health, demographics, and other characteristics of subjects described?	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?	???
	2.4.	Were the subjects/patients a representative sample of the relevant population?	???
	3.	Were study groups comparable?	Yes
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
	3.1.	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
	3.2.	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
	3.3.	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?	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?	Yes
	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.)	Yes
	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.)	Yes
	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?	???
4.	Was method of handling withdrawals described?		???
	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%.)	???
	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?	???
	4.3.	Were all enrolled subjects/patients (in the original sample) accounted for?	???
	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?	N/A
5.	Was blinding used to prevent introduction of bias?		N/A
	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?	Yes
	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
	6.3.	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
	6.4.	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?	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?	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?	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?	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?	No
	7.4.	Were the observations and measurements based on standard, valid, and reliable data collection instruments/tests/procedures?	No
	7.5.	Was the measurement of effect at an appropriate level of precision?	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
	7.6.	Were other factors accounted for (measured) that could affect outcomes?	Yes
	7.7.	Were the measurements conducted consistently across groups?	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.	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
	8.1.	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
	8.2.	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
	8.3.	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
	8.4.	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
	8.5.	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
	8.6.	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
	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?	Yes
	9.1.	Is there a discussion of findings?	Yes
	9.2.	Are biases and study limitations identified and discussed?	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.	Is bias due to study's funding or sponsorship unlikely?		Yes
	10.1.	Were sources of funding and investigators' affiliations described?	Yes
	10.1.	Were sources of funding and investigators' affiliations described?	Yes
	10.2.	Was the study free from apparent conflict of interest?	Yes
	10.2.	Was the study free from apparent conflict of interest?	Yes