EAL

EE: Thermic Effect of Food (2014)

Citation:

Segal KR, Gutin B. Thermic effect of food and exercise in lean and obese women. Metabolism. 1983; 32(6): 581-589.

Study Design:

Randomized Crossover Trial

Class:

A - Click here for explanation of classification scheme.

Quality Rating:

POSITIVE: See Quality Criteria Checklist below.

Research Purpose:

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.

Inclusion Criteria:

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.

Exclusion Criteria:

Refusal to consent
Not meeting inclusion criteria.

Description of Study Protocol:

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.

Anthropometric

Height
Weight
BMI
Percent body fat
Lean body mass (LBM)
Triceps skinfold.

Clinical

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.

Dietary

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.

Data Collection Summary:

Outcome and Other Measures

Measured REE

VO₂ (L per minute)
VCO₂ (L per minute; ml per kg per minute)
RQ
Ventilation (L per minute).

Description of Actual Data Sample:

N=20 females
10 moderately obese (28.9±3.6)
10 lean (29.2±5.1).

Statistical Tests

One-way analysis of variance with repeated measures.

Summary of Results:

Descriptive (Mean±SEM)

	Lean	Obese
Age, years	28.9±3.6	29.2±5.1
Weight, kg*	53.2±7.6	77.9±12.3
Height, cm	53.2±7.6	167±6.2
BMI*	19.3±1.4	27.8±23.3
Percent body fat*	18.8±2.6	37.0±3.5
LBM, kg*	43.1±5.7	48.8±5.9
kcal intake per day	1,666±180	1,878±350

Anaerobic Threshold

	Lean	Obese
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)
Rest
With food*	1.12±0.05	1.33±0.04
Without food*	0.91±0.12	1.13±0.03
Exercise 1: 300kpm per minute
With food*	4.55±0.09	5.10±0.16
Without food*	4.06±0.08	4.86±0.13
Exercise 2: Anaerobic threshold
With food	5.38±0.43	5.76±0.22
Without food	4.87±0.40	5.57±0.22
TEF at rest
RF-R x100%	22.9±2.2	17.5±2.3
(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*	2.54±0.30	1.2±0.24
EF2-E2/RF-R*	2.54±0.23	1.01±0.35
[(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

	Lean	Obese
Rest
With food	0.833*	0.817*
Without food	0.768	0.787
300kpm per minute
With food	0.892*	0.895*
Without food	0.858#	0.851#
Anaerobic Threshold
With food	0.904*	0.919*
Without food	0.880#	0.884#

* 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).

Measurement Process

Number of measurements: Eight
Length of measurements: Five minutes
Steady state: Not defined, but was monitored
RQ: Not an outcome of interest.

Measurement Timing

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.

Author Conclusion:

The key finding of this study was related to the response to the combination of food and exercise. Exercise potentiates the thermic effect of food for the lean women but not the obese women. The large difference in the thermogenic response to the combination of food and exercise was found despite that roughly similar thermogenic response to food alone and to exercise alone.

Funding Source:

University/Hospital:

Columbia University

Reviewer Comments:

Strengths

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.

Generalizability/Weaknesses

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
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?		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