EAL

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

Citation:

Study Design:

Class:

- Click here for explanation of classification scheme.

Quality Rating:

Research Purpose:

To compare the measured resting energy expenditure (REE) in morbidly obese adults prior to surgery with estimated REE by the Harris-Benedict formula using both current weight and ideal weight.

Inclusion Criteria:

Understand and give written consent
Either 45kg or 100% above their ideal body weight, had failed at other approaches to weight reduction
Healthy adults, except markedly obese.

Exclusion Criteria:

Refusal to consent
Not meeting inclusion criteria.

Description of Study Protocol:

Recruitment: Routine nutrition assessment prior to elective gastric bypass surgery
Design: Cross-sectional study
Blinding used: Not blinded.

Statistical Analysis

Paired Student's t-test to analyze differences beteween measured and expected REE
Linear regression analysis to describe the relationship between estimated and measured REE
Multiple regressions with estimated REE and percentage ideal body weight (IBW) as the independent variables performed to include an obesity factor
Linear regressions with height, weight, age and percentage IBW as the independent variables and measured REE as the dependent variable to describe a predictor of REE for morbidly obese patients.

Data Collection Summary:

Timing of Measurements

One measurement time prior to gastric bypass surgery.

Dependent Variables

Measured resting energy expenditure (REE): Abbreviated Weir formula
- IC type: Metabolic Measurement Cart
- Equipment of calibration: Not addressed
- Coefficient of variation using standard gases: Not addressed
- Rest before measure (state length of time rested if available): Not addressed
- Measurement length: Not specified
- Steady state: Measurement continued for a period of five minutes to 15 minutes until evidence of five consecutive stable determinations of VO₂ and VCO₂ were demonstrated
- Fasting length: Two hours
- Exercise restrictions XX hour prior to test: Not addressed
- Room temp: Not addressed
- Number of measures within the measurement period: Not specified
- Were some measures eliminated?
- Were a set of measurements averaged? Yes, continuous measurements of VO₂ and VCO₂ were computed at one-minute interval. Did not address number of measurements.
- Coefficient of variation in subjects measures: No
- Training of measurer: Not addressed
- Subject training of measuring process: Not addressed
- Diet: Not addressed
- Physical activity: Not addressed
- Monitored heart rate: Don’t know
- Body temperature: Don’t know
- Medications administered: Don’t know
- Number of measurements: Continuous measurements of VO₂ and VCO₂ were computed at one-minute interval
- RQ: IC measurements were found to be within ±1.5% of known values for RQ
- Sleep or rest: Rest
- Physical activity: None during measurement; do not know if exercise was restricted prior to measurement.
- Food intake: None during measurement; measurements were taken place after more than two hours following a meal
- Various times in the day: In the morning or in the afternoon.
Predicted REE: Harris Benedict equation.

Independent Variables

Age
Weight, method not described
Percentage ideal body weight (IBW)
Height, method not described
Predicted REE: Harris-Benedict (in regression models).

Description of Actual Data Sample:

Initial N: Not given
Attrition (final N): N=112 (18 males, 94 females)
Individual characteristics
- Generally healthy adults, except morbid obesity. Standard nutritional assessment indices (serum total protein, albumin, total iron binding capacity, hematocrit and white blood cell count) were within normal range.
- Did not specify
  - Circulatory hormones
  - Breathing ability
  - Medical tests and procedures
  - Chemicals (medications, drugs, herbs, caffeine, nicotine, alcohol)
Age: Mean±SD
- Males: 36.5±10.4 years
- Females: 39.8±9.6 years
Ethnicity: Not described
Anthropometrics

Men	Mean±SD
Weight (kg)	146.0±25.6
Height (cm)	175.4±7.0
IBW (percent)	211±35

Women	Mean±SD
Weight (kg)	125.2±23.6
Height (cm)	162.5±12.33
IBW (percent)	221±43

Repeat measures sample
- N=26 healthy subjects (nine males; 17 females).
- N=10 clinically stable patients.
Location: University of Pennsylvania, United States

Summary of Results:

Diurnal Variation between Two Measures Taken on Same Day

The mean percent change from a measure taken one hour apart was 1±2% in 26 healthy subjects (nine male;17 female). The mean percent change between a mid-morning and mid-afternoon measure in 10clinically stable patients was 1±2%.

Measured and Predicted REE

Measured REE was significantly different from expected values (P<0.01) for the males and females when predicted REE was calculated using either current weight or ideal weight
When REE was calculated from current weight, measured REE was 88.4±15% and 89.5±16.9% of expected for the males and females, respectively
When REE was calculated using ideal weight, measured REE was 120.0±39.9% and 138.6±22.3% of expected for the males and females
Only 39% of the morbidly obese patients studied had measured resting energy expenditure that was within ±10% of expected when the standard was calculated from current weight
Only 13% of the obese patients studied had measured resting metabolic rates within ±10% of expected values when the standard was calculated from ideal body weight.

**Measured and Predicted Resting Energy Expenditure (Mean±SD)**
	Expected (kcal/day)		Measured	Measured (% Expected)
	Current Wt.	Ideal Wt.	(kcal/day)	Current Wt.	Ideal Wt.
Males	2,610±421*	1,666±130*	2,274±301	88.4±15.0	120.0±39.9
Females	1,953±254*	1,289±89*	1,751±291	89.5±16.9	138.6±22.3

*P<0.01 versus measured

Linear Regression Analysis

Linear regression analysis showed statistically significant correlation in some instances, but a sufficient amount of the variance in measured REE could not be attributed to the independent variables for the equations to be clinically useful.

Multiple regression analysis with height, weight, age and percentage IBW as the independent variables showed little linear relationship between those indices and measured REE (r=0.22, NS).

**Expected vs. Measured REE**
Sex	Regression Equation	r	P
Males Females	REE=1,487 + 0.30(REEp) REE= 817 + 0.48(REEp)	0.42 0.42	NS <0.01
Males Females	REE=1,332 + 2.12(%IBW) + 0.19(REEp) REE=824 + 1.09(%IBW) + 0.35(REEp)	0.46 0.43	NS <0.01

REE = Measured resting energy expenditure (kcal/day)

REEp = Estimated resting energy expenditure from Harris-Benedict using current weight (kcal/day)

%IBW = percentage ideal body weight

Author Conclusion:

These data indicates that the REE of morbidly obese persons cannot be estimated by the Harris-Benedict formula. In addition, linear regression analysis indicate that there is no simple factor which adjusts for these observed differences, nor does the inclusions of an index describing degree of obesity (%IBW) provide a correction with sufficient sensitivity and specificity for clinical use.

The fact that no statistically significant linear relationship was observed between height, weight, age, % IBW and measured REE indicates that these indices alone are not adequate reflectors of the metabolically active compartment in morbidly obese individuals.”

In general, the Harris-Benedict predictors do not reflect the resting energy expenditures of morbidly obese adults and, therefore, cannot serve as the basis for estimating total daily energy expenditure in this population.

Funding Source:

Government:

NIH

Industry:

Beckman Instruments, American McGraw and Ross Laboratories

Food Company:

Pharmaceutical/Dietary Supplement Company:

Other:

Reviewer Comments:

Strengths

Large sample size for validity study
Reproductivity of the IC measurements was assessed
Appropriate statistics
Conclusions are supported by the results.

Generalizability/Weaknesses

IC measurements protocol was not described in details (measurement timing, condition)
Physical activity was not assessed prior to measurements; dietary intake was not assessed or standardized.
Measures taken only two hours after eating in healthy controls
Did not address limitations: How control subjects were selected; does not report information about withdrawals.

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?	Yes
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?	Yes
	2.2.	Were criteria applied equally to all study groups?	Yes
	2.3.	Were health, demographics, and other characteristics of subjects described?	Yes
	2.4.	Were the subjects/patients a representative sample of the relevant population?	???
3.	Were study groups comparable?		???
	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?	???
	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.)	???
	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?		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%.)	N/A
	4.3.	Were all enrolled subjects/patients (in the original sample) accounted for?	???
	4.4.	Were reasons for withdrawals similar across groups?	N/A
	4.5.	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.)	No
	5.3.	In cohort study or cross-sectional study, were measurements of outcomes and risk factors blinded?	No
	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?	Yes
	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?		???
	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?	No
	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?	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?	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?	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
	8.4.	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
	8.6.	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?		Yes
	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