EE: Thermic Effect of Food (2014)


Segal KR, Chun A, Coronel P, Cruz-Noori A, Santos R. Reliability of the measurement of postprandial thermogenesis in men of three levels of body fatness. Metabolism. 1992; 41(7): 754-762.

Study Design:
Randomized Crossover Trial
A - Click here for explanation of classification scheme.
Quality Rating:
Neutral NEUTRAL: See Quality Criteria Checklist below.
Research Purpose:
  • To determine the reliability of the post-prandial thermogenesis measurement in lean and obese men
  • To characterize the relationship between post-prandial thermogenesis and degree of obesity
  • To investigate the relationship between body fat distribution and post-prandial thermogenesis in men of varying degrees of body fatness.


  • Lean: Less than 16% body fat
  • Average: 18% to 26% body fat
  • Obese: More than 28% body fat
  • Thermic effects of food were calculated in two ways: As the post-prandial minus the fasting energy expenditure, using either the three-hour fasting RMR from the control day (method one) or the 30-minute baseline obtained before the meal on each of the tow meal trials (method two).
Inclusion Criteria:
  • Understand and give written consent
  • Age 25 to 35 years
  • No history of DM or cardiovascular disease
  • Not engaged in regular physical exercise (more than 20 minutes, more than once a week)
  • Weight-state: No more than a 2kg weight loss or gain during the six months before the study.
Exclusion Criteria:
  1. Refusal to consent
  2. Not meeting inclusion criteria
  3. Diseases in subjects that were excluded: Impaired glucose intolerance, DM.
Description of Study Protocol:
  • The order of the three thermogenesis trials was randomized independently for each man
  • The three experimental treatments were:
    • One: Post-absorptive RMR was measured for the last six minutes of every half-hour for three hours while the subjects sat quietly
    • Two and three: Post-prandial RMR was measured for the last six minutes of every half hour for three hours after the subjects consumed a 720kcal mixed liquid meal that was 24% PRO, 21% fat and 55% CHO.
    • The meal was consumed within five minutes. The test was performed twice, on non-consecutive day.


  • Height
  • Weight
  • BMI
  • Percent body fat
  • Body fat content
  • Fat-free mass (FFM)
  • Waist and hip girths
  • Waist:hip ratio.


  • OGTT was performed after an overnight fast (analyzed for glucose and insulin)
  • Aerobic fitness test was determined by a continuous multistage exercise test
  • Monitored heart rate? No
  • Body temperature? No
  • Medications administered? No.

Resting Energy Expenditure

  • IC type: Not specified
  • Equipment of calibration: Yes, every 30 minutes
  • Coefficient of variation using std gases: Not addressed
  • Rest before measure (state length of time rested if available): 30 minutes
  • Measurement length: Six minutes
  • Measurement duration: 180 minutes
  • Steady state: Three to five minutes measures made within a 30-minute period or avoid discomfort; subjects sat quietly
  • Fasting length: 12-hour (overnight)
  • Exercise restrictions XX hour prior to test? Three days
  • Room temp: 24°C
  • Number of measures within the measurement period:
    • Baseline: Three- to five-minute measurements within a 30-minute period, collect three-hour data
    • Experiments: The last six minutes of every half-hour for three hours
  • Were some measures eliminated? No
  • Were a set of measurements averaged? Yes, three five-minutes measurements were averaged
  • Coefficient of variation in subjects’ measures? Yes; less than 3%
  • Training of measurer? Not addressed
  • Subject training of measuring process? Yes.


  • Subjects consumed a weight maintenance diet containing at least 300g CHO of their participation of the study
  • Test meal: 750kcal liquid meal (Sustacal, Mead Johnson):
    • 24% PRO
    • 21% fat
    • 55% CHO.
Data Collection Summary:

Outcome(s) and other measures

  • Measured REE [(VO2, L per minute), VCO2 (L per minute; ml per kg per minute)
  • Blood chemistry: Glucose, insulin.
Description of Actual Data Sample:
  • N=35 men
  • 13 lean (age 29±2 years)
  • 10 average (age 29±2 years)
  • 12 obese (age 31±1 years).

The three groups were matched with respect to:

  • Age
  • Height
  • FFM
  • Level of cardio-respiratory fitness.

Statistical Tests

  • Reliability analysis
  • Two- and three-way ANOVA with repeated measures
  • Correlation coefficient.
Summary of Results:

Descriptive (Mean±SD)

  Lean Average Obese
Age, year 29±2 29±2 31±1
Weight, kg 73.5±2.6 879±3.3 103.5±3.8
Height, cm 178±2 180±2 175±3
Percent fat 11±1 22±1 33±2
RMR, kcal per minutes 1.41±0.06 1.45±0.04 1.49±0.05
Maximal aerobic power
Workload 269±10 263±110 259±12
VO2, ml per minute 3,082±129 3,055±110 3,113±165
Oral glucose tolerance
Resting glucose 86±2 90±2 94±2
Fasting insulin 14±1 18±5 26±4


  • The three groups did not differ with respect to age, height and FFM, but body fat content and total body weight were significantly different
  • Fasting glucose, fasting insulin were significantly greater in obese men than in both lean and average men
  • The fasting, baseline measurement of RMR did not vary significantly across the three treatment days; the coefficient of variation in baseline RMR across trials was less than 3%. The reliability was high, with an intra-class correlation of R=0.958.

Thermic Effect of Meal

  • For both trials A and B, the thermogenic effect of the 720kcal meal, calculated as the post-prandial energy expenditure minus the fasting RMR measured on a separate “control” day (kcal per three hours) was greater for the lean and average men than for the obese men during both trials (P<0.001), but was only marginally different between the lean and average group (P=0.16). The intra-class correlation was R=0.932 (P<0.01).
  • The thermic effect of meal (kcal per three hours) by group was:
  Trial A (kcal Per Three Hours) Trial B (kcal Per Three Hours)
Lean 64 64
Average 54 54
Obese 41 41

[Analyst note: estimated from Figure 1; Trial A and Trial B were the same trial only on different days.]
  • The thermogenic effect of the 720kcal meal, calculated as the post-prandial energy expenditure minus the fasting RMR taken on the same day, the TEF was also significantly blunted for the obese men compared with the lean and average men (P<0.05) but as the concordance between the repeated days was not as high, the intra-class correlation was R=0.819 (P<0.01)
  • The mean values for two trials were similar and the measurement of thermogenesis by indirect calorimetry was highly reproducible with a reliability coefficient of R=0.932 (P<0.001)
  • Across all groups, thermogenesis correlated strongly with percent body fat (R=-0.64, P<0.01), but with the average men, thermogenesis was uncorrelated with percent body fat (R=0.09) but highly correlated with the glucose response to the meal (R=-0.75, P<0.05). Thus, factors other than body fatness, such as insulin sensitivity, may determine thermogenesis within this heterogeneous middle group.
  • The day-to-day intra-individual coefficient of variation in the thermic effect of food was approximately 5.7%.

Measurement Process

  • Number of measurements: Six
  • Length of measurements: The last six minutes of every half hour for three hours
  • Steady state: Not addressed
  • RQ: Not measured.

Measurement Timing

  • Sleep or rest: Rest
  • Physical activity: No
  • Food intake: Not during measurements
  • Various times in the day: Morning.
Author Conclusion:
  • This study demonstrated that the thermic effect of a mixed meal can be measured reliably by indirect calorimetry when careful attention is paid to acclimatization of the subjects to the test procedure
  • The reliability of the estimation of the thermic effect of food is enhanced by the use of fasting metabolic rate data collected over the same period of time on separate days, instead of a single primal fasting measurement
  • The results of the present study suggest that there is a strong independent correlation between the degree of fatness and post-prandial thermogenesis is distinctively lean and distinctly obese individuals that is independent of insulin action, whereas within a group of men of in-between fatness, insulin sensitivity is a major important determinant of thermogenesis
  • The increase in metabolic rate after a mixed meal is blunted in obese subjects compared with subjects of low or moderate body fatness, and in those more than 28% body fat, the thermic effect of a meal is nearly consistently blunted
  • These results demonstrate that post-prandial thermogenesis is reliable, confirm the putative defective thermogenesis in obesity and indicate the importance of careful body composition measurement and classification in the study of thermogenesis and obesity.
Funding Source:
Government: NIH
Reviewer Comments:


  • Statistical reliability was performed and determined by the intraclass correlation method
  • Cares were taken to match three groups according to their age, height, FFM and fitness
  • Great study design
  • Clearly defined fatness levels, and methods of thermic effects of food calculations.


  • Limitations were not described
  • Questionable validity of indirect calorimeter
  • Applied only to healthy young men
  • Applications to IC question I: Obese patients may be less sensitive to the nutrition composition of meal regarding to their REE measurements.
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? 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? 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? 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? ???
  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? ???
  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