EE: Old and Very Old Populations (2006)

Citation:

Reed GW, Hill JO. Measuring the thermic effect of food. Am J Clin Nutr. 1996;63:164-169.

PubMed ID: 8561055
 
Study Design:
Prospective Cohort Study
Class:
B - Click here for explanation of classification scheme.
Quality Rating:
Neutral NEUTRAL: See Quality Criteria Checklist below.
Research Purpose:
  1. To evaluate the effect of the duration of measurement on the TEF
  2. Develop a model of the TEF to reduce some of the measurement variation and thus improve understanding of the factors that influence TEF.

Definitions

  • Steady state: Not specified
  • Energy expenditure at the end of meal test: kJ/h (or kcal/h)
  • TEF: expressed as percentage of meal size.
Inclusion Criteria:
  1. Understand and give written consent
  2. Completed a RMR measure in the energy metabolism unit at Vanderbilt University.
Exclusion Criteria:
  1. Refusal to consent
  2. Not meeting inclusion criteria.
Description of Study Protocol:

ANTHROPOMETRIC

  • Ht measured? Not specified
  • Wt measured? Yes
  • Fat-free mass measured? Yes, underwater weighing.

CLINICAL

  • Monitored heart rate? Not specified
  • Body temperature? No
  • Medications administered? Not specified

Resting energy expenditure

  • IC type: SensorMedics 2900
  • Equipment of Calibration: Not specified – likely since a energy metabolism lab?
  • Coefficient of variation using std gases: No
  • Rest before measure (state length of time rested if available): 45 min
  • Measurement length: Baseline was 30 min; then 10 min every 30 mins
  • Steady state: Not specified
  • Fasting length: Overnight
  • Exercise restrictions XX hr prior to test? Not specified
  • Room temp: Not specified
  • No. of measures within the measurement period: 13
  • Were some measures eliminated? Not specified
  • Coefficient of variation in subjects’ measures? Not specified
  • Training of measurer? Likely
  • Subject training of measuring process? Varies

DIETARY

Test meal size and composition varied for different studies; a fixed meal size of ~1000 kcal and 40% energy as fat and in other related to subject’s usual intake based on diet records (i.e., 25% usual intake). All meals contained 15% energy as protein.

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. TEF as aurea under the response curve minus the 6-hr RMR (extrapolated from baseline);
  3. Independent variables of weight, height, age, BMI, and fat-free mass, fat mass.

Blinding used: No

Description of Actual Data Sample:
  • N=131 independent baseline meal tests measured from 1988-1992
  • All measurements represented baseline tests, before any intervention
  • 77 females (59%) and 54 males
    • Mean age, y: 38.1
    • Range: 18-65.

Statistical tests

Nonlinear curve fitting was computed by finding the area under the smooth curve (smothered area). The smoothed area (original TEF), and the smooth-curve parameters were compared with subject (FFM, fat mass, percentage fat, age, and sex) and meal characteristics (size and content) using multiple regression analysis; nonparametric sign test was used to test whether medians were different from zero; t tests whether means were different from zero; multiple regression analysis to compare the TEF area and model parameters with subject and meal characteristics.

Summary of Results:

ANTHROPOMETRIC

(No SD given)

Men and Women

Mean

Range

Wt, kg

88.6 49.8-130.2

BMI

21.6±2.7 17.0-29.0

Fat-free body mass

56.5 37.6-82.8

Fat mass, %

35.4 8.7-51.3

DIETARY

  • Kcals eaten varied: ~945 kcal/test meal mean
  • Test meal range, kcal: 650-1394.

Meal composition

  • Mean fat kcal, %: 36.6
  • Fat kcal range, %: 24-65;
  • Mean CHO kcal, %: 48.4
  • CHO kcal range, %: 20-69
  • All studies contained 15% protein kcal.

MEASUREMENT PROCESS

  • Number of measurements: 13
  • Length of measurements: Initially 30 min, then 10 min every 30 minutes thereafter
  • Steady state: Not specified
  • RQ: Not specified.

ENERGY EXPENDITURE ABOVE RMR

  • The group mean energy expenditure difference at the end of 6 hr to RMR before the test meal was 3.8 kcal/h [Analyst note: 0.063 kcal/min or 22.8 kcal over the 6-hr measurement period]; the median difference was 2.99 kcal/h [Analyst note: 0.050 kcal/min or 17.9 kcal over the 6-hr measurement period?] (P<0.001).
  • The median differences and the 25th percentiles of the differences distributions indicate that the >75% of subjects had a positive component of TEF difference between 5 and 6 h post-prandial.
  • If use 6 hr TEF as total TEF, then the median percentage of “missed” (or unmeasured) TEF at 3, 4, and 5 hr would be 40, 22.5 and 9.1%, respectively
  • If only smaller meals were used (i.e., <800 kcal), the mean and median differences in TEF at 6 and 6 hours are significantly positive (P>0.05) and the 25th percentile is positive. For these smaller meals, 10% of the total TEF was not measured at 4 h.
  • The TEF was related to meal size in a quadratic fashion and related to the subject’s FFM;
  • The peak EE was related to meal size and FFM; EE correlated negatively with the subject’s body fat %.
  • A trend (P<0.06) for the peak to decrease with increases in relative meal fat content.
  • Meal size and FFM tend to increase the peak; subject’s body fat and meal size squared tend to lower the peak; meal size and subjects body fat tends to move the peak further out. The time of the peak was related to meal size in a positive linear fashion.
Author Conclusion:

As stated by the author in body of report:

  • “Our study repots that a 3-h TEF measurement can miss >40% of the total TEF and a 4-h TEF measurement can miss 22.5% of the total TEF. Even for meals providing ~800 kcals , 10% of 6-hr TEF occurs between 4 and 6 hr."
  • “Our new data indicate that nonobese subjects show an earlier and higher peak TEF then do obese subjects... and that total TEF will differ between obese and nonobese subjects [Thus, a measurement lasting an additional 2 h may eliminate that difference].”
  • “The curve is not intended to predict individual TEF based on subject and meal characteristics but it is to give a more detailed description of TEF measure... we believe that two individuals can have the same area under the curve, but drastically different TEF curves and the usual trapezoid area method of measuring TEF would not pick this up.”
  • “These data indicate that the shape of the TEF curve differ between lean and obese individuals... [therefore] when TEF is measured to 3 h there may be differences but this disappears when TEF is measured to 6 h.”
  • “The new model improves the power to identify factors that influence TEF... the positive linear and negative quadratic effect reported previously could be an indication of a meal size threshold effect... once the meal reaches a certain size, no increase in meal size will increase TEF."
  • “Overall, as meal size increase, the peak TEF increases and occurs at a later time after meal ingestion and total TEF increases and there is a direct positive relation between the amount of FFM of the subject and both the peak and total TEF... the body fat content of the subjects (either amount or percent) appears to effect the shape of the TEF response but not the total amount of the TEF... we recommend TEF measurements last =5 hr."
Funding Source:
University/Hospital: Belfast City Hospital
Reviewer Comments:

Strengths

  • “Independent measures represent a broad age range and extreme body fat % (i.e., 8.7-51.3%)”
  • Advanced use of AUC statistical analysis.

Generalizability/Weaknesses

  • “Convenience sampling bias”
  • “Not generalizable to old and oldest old (i.e., >65 y)
  • An intervening variable was variation in test meal size and composition (i.e., fat kcal % range was from 24-65)
  • These are important variables on RMR measurement accuracy not measured are steady state, exercise restrictions, and subject training of measuring.”
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? No
  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? 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
  5.3. 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? N/A
  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