EAL

EE: Harris-Benedict: Obese and Nonobese (2005)

Citation:

Study Design:

Class:

- Click here for explanation of classification scheme.

Quality Rating:

Research Purpose:

To determine if RMR is different in obese African-American women compared to a closely-matched group of obese Caucasian women

Inclusion Criteria:

1. Understand and give written consent

2. Diseases in subjects that were allowed: metabolic disorders

3. Medications allowed: any medications that would affect heart rate or RMR

4. African American or Caucasian

5. premenopausaul, nonsmokers, sedentary, defined as exercising less than once per week for the previous 6 months.

6. obese

Exclusion Criteria:

1. Refusal to consent

2. Not meeting inclusion criteria

Description of Study Protocol:

Definitions:

“Steady state”- not addressed

Term:

RMR-resting metabolic rate

TBW-total body weight

LBM-lean body mass

RER-respiratory exchange ratio

RHR-resting heart rate

Anthropometrics:

Ht measured ? yes

Wt measured ? yes

Fat-free mass measured? yes

Siri equation was used for calculating % body fat for both groups.

CLINICAL:

Monitored heart rate? yes

Body temperature? no

Medications administered? no

Blood pressure, respiratory exchange ratio (RER)

Resting energy expenditure:

IC type: ventilated hood system

Equipment of Calibration:

Coefficient of variation using std gases: Yes, +/- 4%

Rest before measure (state length of time rested if available): 30 min

Measurement length: 30 min

Steady state: not addressed

Fasting length: 12 h

Food intake : after 12 h fast, dietary intake prior to IC study were not controlled

Exercise restrictions XX hr prior to test? no; none during measure

Room temp: not specified

No. of measures within the measurement period: not specified

Were some measures eliminated? no

Were a set of measurements averaged? not addressed

Coefficient of variation in subjects measures? yes

Training of measurer? no

Subject training of measuring process? no

DIETARY

Dietary intake prior to IC measurements were not controlled.

Intervening factor:

Premenopausal, nonsmoker, measurements were taken during the early follicular phase of the menstrual cycle

Statistical tests:

Student’s paired t-test

ANCOVA

Pearson correlation coefficient

Data Collection Summary:

Outcome(s) and other measures

1. Measured RMR and RER

2. Body composition

3. Maximal aerobic capacity (VO2 max)

4. Girth strength

5. Independent variables of weight, height, age, BMI, and fat-free mass

6. Predicted metabolic rate by HB

Blinding used: No

Description of Actual Data Sample:

N= 47 women (25 African Americans, 22 Caucasians)

Age 35 ±1 y (mean ± sem)

Summary of Results:

Descriptive (mean ± sem)

African American	Caucasians
Age,y	34 ± 1	36 ± 2
Ht,cm	164.6 ± 1.9	165.4 ± 1.5
Wt,kg	99.0 ± 3.2	91.1 ± 3.6
BMI	36.1 ± 1.3	33.2 ± 1.1
%body fat	44.8 ± 1.2	45.6 ± 1.3
fat mass,kg	45.2 ± 3.1	42.3 ± 2.6
lean mass,kg	53.7 ± 1.7 *	48.8 ± 1.2
RER	0.75 ± 02	0.74 ± .02
RHR,bpm	73 ± 2	74 ± 2
MHR,bpm	183 ± 3	182 ± 2
VO2max	2.23 ± .13	2.41 ± .09

*significantly different from Caucasians at p<0.05 level

The two groups were not significantly different in age, ht, wt, BMI, %body fat, fat mass; or chest, arm waist, hip, thigh, and calf circumferences. Although % body fat was not different between the two groups, African American women had significantly more LBM than Caucasian women. RER and RHR were similar between races, as were metabolic measurements during maximal exercise.

RMR

When adjusted for TBW, RMR for African Americans was significantly lower than Caucasians by 9%. An even larger difference (-12%) for African Americans compared to Caucasians was found when RMR was adjusted for LBM.

RMR was significantly (P<0.000) related to body wt (r=0.69) and LBM (r=0.61) in these obese women.

RMR was also significantly related (r=0.51-0.56, p<0.000) to VO2max for both groups.

Predicted RMR for the African Americans was the same as measured RMR, whereas Caucasian women expended about 13% more energy than predicted

MEASUREMENT PROCESS:

Various times in the day: morning

INDIVIDUAL CHARACTERISTICS

Sedentary, premenopausal, obese nonsmokers, free from any metabolic disorder

Author Conclusion:

“In summary, the results from this study indicate that there are significant differences in adjusted RMR between inactive, obese African American and Caucasian women. It is likely that the lower RMR for African American women contributes to the high prevalence of obesity in the African American female population. Thus, when examining the metabolism of premenopausal women, it is critical to control for racial differences in metabolic rates. Due to the metabolic differences found in this study, it is particularly important to control for race when creating energy expenditure prediction equations for obese women.”

“When compared to RMR to measured RMR, racial differences were found. RMR for obese Caucasian women were significantly under predicted, while the predicted RMR for African Americans did not differ from their measured RMR.”

“It appears that in a homogeneous group of obese premenopausal Caucasian women, the Harris-Benedict equation will under predict true RMR by about 628 kJ/d (150 kcal /d).”

“Prescribed energy intakes can be estimated accurately for obese African-American women using the Harris-Benedict equation.”

Funding Source:

University/Hospital:

George Washington University

Reviewer Comments:

Strengths:

Case and control groups were matched in demographics and body composition.
Intervening factors were considered: menstrual cycle, sedentary lifestyle, and nonsmokers.
Great study design with appropriate statistics.
Comparison of measured RMR and predicted RMR by HB equation were performed by race.

Generalizability/Weaknesses:

Results only applied to sedentary obese female population
Limitations were not discussed.

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?		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