EE: Thermic Effect of Food (2014)
Segal KR, Gutin B. Thermic effect of food and exercise in lean and obese women. Metabolism. 1983; 32(6): 581-589.
To examine the thermic responses of weight-stable lean and obese women to food and two levels of exercise:
- The same absolute level for all women
- A level related to each woman’s aerobic fitness.
- Understand and give written consent
- Healthy women, ages 20 to 40
- Free of metabolic disease
- Weight stable: No more than 2kg change in weight for more than six months.
- Refusal to consent
- Not meeting inclusion criteria.
- All subjects participated in six experiments in random order. Thermogenic response were monitored under six conditions:
- During five minutes of bicycle exercise at a workload of 300kpm per minute with and without a 910kcal mixed meal
- Cycling at a workload just below the anaerobic threshold with and without food
- Rest with and without food.
- Each subject completed the six treatments within a two- to three-week period.
- Percent body fat
- Lean body mass (LBM)
- Triceps skinfold.
- Monitored heart rate? Not addressed
- Body temperature? Not addressed
- Medications administered? No.
Resting energy expenditure
- IC type: Open circuit respiratory
- Equipment of Calibration: Yes, with gases of known concentration
- Coefficient of variation using std gases: Not addressed
- Rest before measure (state length of time rested if available): 30 minutes
- Measurement length: Five minutes every half hour
- Measurement duration: Four hours
- Steady state: Monitored if steady state was achieved or not
- Fasting length: Overnight
- Exercise restrictions XX hr prior to test? Yes
- Room temp: 21° to 24°C
- Number of measures within the measurement period: Eight
- Were some measures eliminated? No
- Were a set of measurements averaged? Yes, eight half-hourly values for each treatment day were averaged over the four-hour period
- Coefficient of variation in subjects’ measures? No
- Training of measurer? Not addressed
- Subject training of measuring process? Not addressed.
- Each woman completed a three-day dietary record (two week days and one weekend day)
- Test meal contains 910kcal: 14% PRO, 46% CHO and 40% fat.
Outcome and Other MeasuresMeasured REE
- VO2 (L per minute)
- VCO2 (L per minute; ml per kg per minute)
- Ventilation (L per minute).
- N=20 females
- 10 moderately obese (28.9±3.6)
- 10 lean (29.2±5.1).
Statistical TestsOne-way analysis of variance with repeated measures.
|Percent body fat*||18.8±2.6||37.0±3.5|
|kcal intake per day||1,666±180||1,878±350|
|workload, kpm per minute||390±126||375±79|
|VO2, L per minute||1.01±0.25||1.11±0.16|
|VO2, ml per kg per minute*||19.02±3.19||1.11±0.16|
|VO2, ml per kg, LBM per minute||23.42±3.81||23.46±4.11|
|kcal per minute||4.93±1.36||5.35±0.82|
*Significant difference between groups at P<0.05 level.
Caloric Expenditure at Six Conditions (Mean±SEM)
|Lean (kcal Per Minute)||Obese (kcal Per Minute)|
|Exercise 1: 300kpm per minute|
|Exercise 2: Anaerobic threshold|
|TEF at rest|
|(RF-R) x 240 minutes kcal||50.0±4.6||47.0±6.0|
|TEF during exercise|
|EF1-E1/E1 x 100, %*||12.1±1.0||4.9±1.1|
|EF2-E2 x 100, %*||10.6±0.9||3.6±1.2|
|(EF1-E1) x 40 minutes, kcal*||19.6±1.5||9.7±2.4|
|(Ef2-E2) x 40 minutes, kcal*||20.1±1.7||7.5±2.4|
|Potentiation of TEF by exercise|
|[(EF1-E1)-(RF-R)] x 40 minutes, kcal*||11.3±1.3||1.8±1.9|
|[(EF2-E2)-(RF-R)] x 40 minutes, kcal*||12.0±1.4||-0.4±2.3|
* Significant differences between groups at P<0.01 level.
Effect of Food and Exercise on Respiratory Exchange Ratio
|300kpm per minute|
* Significantly higher than fasting value at P<0.05 level.
# Significantly higher than resting value at P<0.05 level.
Thermic Effect of Food (TEF)
- Over the four-hour period, the thermic effect of food at rest was similar for the lean and obese groups: 50kcal and 47kcal, respectively
- Eating before exercise increased the exercise metabolic rate by 11% for the lean women and by 4% for the obese women (P<0.005)
- Exercise potentiated the thermic effect of food for the lean women but not for the obsess women: The thermic of food was 2.54 times greater during exercise than at rest for the lean group, but only 1.01 times greater for the obese women (P<0.005).
- Number of measurements: Eight
- Length of measurements: Five minutes
- Steady state: Not defined, but was monitored
- RQ: Not an outcome of interest.
- Sleep or rest: Depends on the treatment
- Physical activity: Yes, depends on treatment
- Food intake: Depends on the treatment
- Various times in the day: Morning.
- Comprehensive study design with appropriate statistics
- Assessment of regular dietary practice and physical activity levels were done to ensure that all participants in two groups are comparable
- Exercise and measurement protocol were described in detail
- Randomization of the orders of the six experiments were performed.
- Did not address if any of the subjects are habitual smokers. Smoking could be a confounding factor for TEF.
- Limitations of the study were not discussed.
Quality Criteria Checklist: Primary Research
|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|
|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?||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|