Adult Weight Management

AWM: Estimating Resting Metabolic Rate (RMR) (2014)

Citation:

Faria SL, Faria OP, Menezes CS, de Gouvea HR, de Almeida Cardeal M. Metabolic profile of clinically severe obese patients. Obes Surg. 2012; 22(8): 1,257-1,262.

PubMed ID: 22527595
 
Study Design:
Cross-Sectional Study
Class:
D - Click here for explanation of classification scheme.
Quality Rating:
Neutral NEUTRAL: See Quality Criteria Checklist below.
Research Purpose:
To aim to evaluate the basal metabolic rate (BMR) among clinically severe obese patients pre-operatively. The BMR was compared to a control group with predictive formulas and correlated with body composition. 
Inclusion Criteria:
  • Severely obese with BMI more than 40kg/m2 or BMI more than 35kg/mwith co-morbidities
  • Control group of normal weight or overweight subjects (BMI less than 30kg/m2)
  • Provided written informed consent.
Exclusion Criteria:
  • Patients with thyroid disease
  • Those who used drugs with a thermogenic effect and affecting metabolism (i.e., green tea extract, caffeine and guarana capsules)
  • Minors less than 18 years of age, elderly patients (more than 65 years of age) and pregnant women were also excluded.
Description of Study Protocol:

Recruitment

Patients were recruited from the Gastrocirurgia de Brasilia Clinic.

Design

Cross-sectional study.

Blinding Used

Implied with measurements.

Statistical Analysis
  • The Mann-Whitney U statistical test was applied to analyze BMR values of the two groups measured by IC and calculated by predictive formulas
  • Sample size was calculated and the power of test was higher than 0.80
  • As a basis of sample size calculation, an experimental group of 130 participants and a control group of 63 were seen as the structure that would provide an 80% power of the test to detect clinically any significant differences in BMR between the groups assuming an average difference of 400kcal per day with a weighed standard deviation of 350kcal per day for a significance level of 5%.
Data Collection Summary:

Timing of Measurements

All measurements made on the same day.

Dependent Variables

  • Body composition data were obtained using multi-frequency bioelectrical impedance (Inbody 720-Biospace) that measured total body weight in kilogram, percentage of body fat (BF%) and FFM
  • The FFM was calculated by subtracting the weight of total BF from the total body weight
  • Basal metabolic rate (BMR) measured by indirect calorimetry (IC) using the Cosmed Fitmate for 15 minutes in the supine position after fasting for 12 hours in a room with controlled air conditioning maintained at 22° Celsius
  • The obtained values were adjusted per kilogram of current body weight in both groups and compared with those calculated from the current weight by the predictive equations
  • Predictive equations used:
    • Harris-Benedict
    • Cunningham
    • Horie-Waitzberg and Gonzalez
    • Mifflin-St. Jeor
    • Bobbioni-Harsch.

Independent Variables

  • Severely obese women
  • Normal weight and overweight controls.
Description of Actual Data Sample:
  • Initial N: 193 subjects (16.92% male, 83.1% female)
  • Attrition (final N): 193 subjects
  • Age: Mean age of the obese group 35.38 years vs. 31.83 in the control group
  • Other relevant demographics: Mean FFM percent of the obese group 50% vs. 71% in the control group
  • Anthropometrics: Mean BMI (kg/m2) of the obese group 41.89 vs. 24.46 in the control group
  • Location: Brazil.
Summary of Results:

Key Findings

  • Clinically severe obese patients had higher absolute BMR values and lower adjusted BMR values (P<0.0001)
  • A positive correlation between fat free mass and a negative correlation between body fat percentage and BMR were found in both groups
  • Among the clinically severe obese patients, the formulas of HW&G and HBE overestimated BMR values (P=0.0002 and P=0.0193, respectively) while the BH and CUN underestimated this value
  • Only the MSJE formulas showed similar results to those of indirect calorimetry.
Author Conclusion:
The clinically severe obese patients showed low BMR levels when adjusted per kilogram per body weight. Body composition may influence BMR. The use of the MSJE formula may be helpful in those cases where it is impossible to use IC.
Funding Source:
University/Hospital: University of Brazil
Reviewer Comments:
  • Questionable validity of indirect calorimeter
  • The authors mentioned a limitation was that a limited amount of research tracing the metabolic profile of morbidly obese patients, which could provide the basis for a broader comparison of results as well as the absence of standardization of the methodology for BMR adjustment.
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? 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) 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
  3.4. 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
  3.6. 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? Yes
  4.1. Were follow-up methods described and the same for all groups? Yes
  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%.) Yes
  4.3. Were all enrolled subjects/patients (in the original sample) accounted for? Yes
  4.4. Were reasons for withdrawals similar across groups? Yes
  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.) Yes
  5.3. In cohort study or cross-sectional study, were measurements of outcomes and risk factors blinded? Yes
  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? Yes
  6.6. Were extra or unplanned treatments described? Yes
  6.7. Was the information for 6.4, 6.5, and 6.6 assessed the same way for all groups? Yes
  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? 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? ???
  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
  7.7. Were the measurements conducted consistently across groups? Yes
8. Was the statistical analysis appropriate for the study design and type of outcome indicators? Yes
  8.1. 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)? No
  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? Yes
9. Are conclusions supported by results with biases and limitations taken into consideration? Yes
  9.1. Is there a discussion of findings? Yes
  9.2. Are biases and study limitations identified and discussed? Yes
10. Is bias due to study's funding or sponsorship unlikely? Yes
  10.1. Were sources of funding and investigators' affiliations described? Yes
  10.2. Was the study free from apparent conflict of interest? Yes