EE: Application of RQ (2005)

Citation:

Surina DM, Langhans W, Pauli R, Wenk C. Meal composition affects postprandial fatty acid oxidation. Am J Physiol. 1993;264 (Regulatory Integrative Comp. Phsyiol. 33): R1,065-R1,070.
 

PubMed ID: 8322958
 
Study Design:
Non-Randomized Crossover Trial
Class:
C - Click here for explanation of classification scheme.
Quality Rating:
Neutral NEUTRAL: See Quality Criteria Checklist below.
Research Purpose:
  1. To investigate whether fat content of a single meal influences fat oxidation in men.
  2. To compare fax oxidation after a high fat meal (containing medium and long-chain fatty acids) with a equicaloric high carbohydrate meal.

Definitions

  • Steady state: Not defined
  • Healthy: 8-15% body fat
  • Lean: 8% body fat
  • Plump: 16-19% body fat
Inclusion Criteria:
  1. Understand and give written consent
  2. Weight stable over preceding 2 months
  3. No history of diabetes or obesity.
Exclusion Criteria:
  1. Refusal to consent
  2. Not meeting inclusion criteria
  3. Diseases in subjects that were excluded: diabetes and obesity.
Description of Study Protocol:

ANTHROPOMETRIC

  • Ht measured? yes
  • Wt measured? yes
  • Fat-free mass measured? Yes; 3 skinfold measurements of 7 different body sites;

CLINICAL

  • Monitored heart rate? Yes, through a polarized chest belt
  • Body temperature? No
  • Medications administered? Excluded

Resting energy expenditure

  • IC type: Oxyconsigma with ventilated hood
  • Equipment of Calibration: No
  • Coefficient of variation using std gases: No
  • Rest before measure (state length of time rested if available): “sedentary conditions”
  • Measurement length: 15-60 mins
  • Steady state: “used heart rate to detect “abrupt fluctuations that would affect recordings
  • Fasting length: 8.75-11.75
  • Exercise restrictions XX hr prior to test? yes; overnight 8-12 hrs
  • Room temp: not specified
  • No. of measures within the measurement period: 1
  • Were some measures eliminated? Not specified
  • Were a set of measurements averaged? 15 one-minute for baseline; 60 “postprandial
  • IF avg, identify length of each measure & no. of measurements?
  • Coefficient of variation in subjects measures? No
  • Training of measurer? Likely
  • Subject training of measuring process? Discussed in consent process

DIETARY

  • Used bomb calorimeter to identify gross energy of meal prepared and consumed

Intervening factor:

Data Collection Summary:

Outcome(s) and other measures

  1. Measured REE [(VO2 l/min), VCO2 (l/min; ml/kg/min), RQ, ventilation (l/min)].
  2. Timing of respiratory measaures (5 time points)
  3. Blood sampling, including plasma insulin and metabolites
  4. Independent variables of weight, height, age, BMI,and fat-free mass, fat mass.

Blinding used: No

Description of Actual Data Sample:
  • N=15 Caucasian males, aged 27-34 yr (mean 30.2±SD not provided)
  • Range: 27-34

Statistical tests

  • Within subjects two-way ANOVA; Tukey’s post-hoc comparisons, p vales <0.05 were significant
Summary of Results:

ANTHROPOMETRIC

Men Mean Range

Wt, kg

73.76 59-88

Ht, cm

181.0 168-189

Body fat, %

10.3 7-17

RQ RESULTS (Paper reports in ±SEM)

  • There was a significant difference in RQ between diets [F(1,12) = 7.413, P<0.01] and between times [F (4,12) = 15.325, P<0.001]
  • Fasting group mean RQ was 0.88±0.02 (SEM) and 0.85±0.05 in High fat and High CHO diet groups, respectively.
    [Assuming normality and ±2 SD, 98% of High Fat group would have an RQ fall within 0.74-1.02 and 98% of High CHO group would have an RQ fall within 0.49-1.21]
  • Group mean RQ rose to 1.0±0.01(SEM) and 0.98±0.01 (SEM) approximately 10 minutes after finishing a high CHO and high FAT diet, respectively.

[Analyst note: this numbers taken from Figure 1 and the X-axis is marked to that the minutes are from baseline measure. If use text, then the 30 minute data point on the Figure is actually approximately 10 minutes after eating.]

  • At 2.7 hr later, group mean RQ for the high CHO diet was ~0.99±0.02 (SEM) and ~0.90±0.02 for the high FAT diet.

[Analyst note: group mean±SEM were taken from Figure 2 Used 1 in per 1 ft ruler markings; assuming normality High CHO range 0.835-1.145 and High FAT range is 0.735-1.055 160 after finishing eating.]

Calculations

  • v15 X 0.02=0.077 (1 SD)
  • 0.077 X 2=0.155 (2 SD)

RQ remained close to 1.0 in the high carbohydrate diet After the high fat meal, however, the RQ decreased and was significantly lower than after the high-carbohydrate meal at 120 (P<0.01) and 180 min (P<0.001) from meal initiation.

Group mean RQ range over 180 minutes ranged from 1.0 at 30 minutes and then slightly decreased (~0.98) approximately 40 minutes after eating but then remained at 1.0 at 100 and 160 minutes following the High carbohydrate meal.

[Analyst note: this numbers taken from Figure 1 and the X-axis is marked to that the minutes are from baseline measure. If use text, then the 30 minute data point on the Figure is actually approximately 10 minutes after eating.]

Author Conclusion:

As stated by the author in body of report

In our study, the lower RQ value after the HF meal can be attributed to fat oxidation because the proteincontent of the two meals was roughly identical and because the amount of fat in a meal does not seem to alter the rate of protein oxidation.”

“It can be estimated that beginning at 2 h after the HF meal, between 15-20% of fuel burned was fat.”

“It is worth mentioning here that the HF meal resembled an average American breakfast in content, taste, appearance, and consistency. The energy content was high for al subjects regardless of their size and metabolism.”
Funding Source:
Reviewer Comments:

Strengths 

  • Controlled for kcal content of each meal; no attempt was made to equate energy content of test meals with energy expenditure of the individuals because of within-subjects design.

Generalizability/Weaknesses

  • “Generalizable to nonbese and obese adult males and short-term effects of high fat or high CHO diet consumption”
  • “Did not include sampling methods but definitely motivated subjects if they agreed to tolerate 4 hrs of IC measures
  • These are important variables on REE measurement accuracy did not clearly define steady state or quantify rest before 1st measure; Respiratory measures continued for 60 min intervals for 4 hours and there were 2-15 min and two 40 min breaks.
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? No
  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? 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? 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? Yes
  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? Yes
  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