EE: Ephedra (2005)

Citation:
 
Study Design:
Class:
- Click here for explanation of classification scheme.
Quality Rating:
Research Purpose:
  1. To validate the studies of Lanzola et al.
  2. To compare changes in skin temperature but also changes in internal temperature with changes in metabolic rate as measured by indirect calorimetry after use of caffeine to induce a thermogenic effect.
Inclusion Criteria:
  1. Understand and give written consent
  2. Healthy young men, nonobese
  3. Volunteers
  4. Nonsmoking
  5. Normal physical activity levels
  6. Not on medications known to influence the metabolic rate.
Exclusion Criteria:
  1. Refusal to consent
  2. Not meeting inclusion criteria
  3. On medications known to influence the metabolic rate.
Description of Study Protocol:

ANTHROPOMETRIC

  • Ht measured? Yes
  • Wt measured? Yes
  • Body surface measured by use of the formula of Du Bois and Du Bois (1916)
  • Fat-free mass? No.

CLINICAL

  • Monitored heart rate? Not mentioned
  • Body temperature? Yes
  • Medications administered? No
  • Same for all subjects; driven to research center at 7:00 am.

Resting energy expenditure

  • IC type: Ventilated hood
  • Equipment of Calibration: Before measurements; calibrated against standard gases and air and once a week calibrated against alcohol burning; variability was 2.8%
  • Coefficient of variation using std gases: Yes
  • Rest before measure: About 15 min. before metabolic rate measurements
  • Measurement length: Initial about 45 min (RMR); after caffeine/no caffeine loading, coffee-induced metabolic rate measured for another 3 h; metabolic rate over periods of 2.5 min.
  • Steady state: Not mentioned
  • Fasting length: Fasted after 11 pm the evening prior (app. 8 h) and instructed to abstain from alcohol and caffeine 16 h before the measurements were taken
  • Exercise restrictions: No strenuous physical activity the day preceeding the measurements
  • Room temp: Room temp of 22.5 (varied between 21 and 25 degree C); measured every 15 min.
  • No. of measures within the measurement period: 4 measurements were taken in a random and blinded to subject; two with and two without caffeine.
    To avoid carry-over effects, consecutive measurements were separated by at least 2 days.
  • Were some measures eliminated? Not mentioned
  • Were a set of measurements averaged? Yes
  • Coefficient of variation in subjects measures? Not mentioned
  • Training of measurer? Not mentioned
  • Subject training of measuring process? Not mentioned.

DIETARY

  • Subjects consumed 150 ml decaffeinated coffee with or without 200 mg added caffeine (blind, random order). No milk or sugar was added.
  • Intervening factor: Age of subjects and ethnicity were not provided.
Data Collection Summary:

Outcome(s) and other measures

  1. Resting metabolic rate (RMR); RMRmean + RMRmeasured - RMRpredicted.
  2. Height, weight, body temperature
  3. Temperatures of the abdominal wall and internal (rectal) were measured.

Blinding used: Yes.

Description of Actual Data Sample:
  • N=12 healthy young men (volunteers) (ages not provided).
  • Statistical tests: ANOVA used to assess the effect of caffeine on metabolic rate, mean skin temperature, abdominal temperature and internal temperature. Pearson’s correlations; Multiple stepwise regression analysis was used to study the relationship between energy expenditure and body temperature. Mean values ±SD.

Summary of Results:

ANTHROPOMETRIC

Men Mean±SD

Wt, kg

74.5±8.8

Ht, cm

184.5±7.5

BMI

21.9±2.6

Body surface area, m2

1.97±0.13

CAFFEINE

After caffeine consumption, the metabolic rate increased immediately with 0.2±kJ/min (0.05 kcal/min) (P<0.05) and remained elevated for the 3 h during which measurements were taken (caffeine-induced metabolic rate).

Mean total caffeine-induced thermogenesis was 0.30±0.20 kJ/min (0.07 kcal/min) or 54±36kJ over 3 h (12.9±08.8 kcal/3 h), which means an increase in the metabolic rate of 7±4% during 3 h.

Coffee consumption without caffeine did not result in a statistical increase in the metabolic rate (mean increase 0.03±0.18 kJ/min (0.01 kcal/min).

There were no differences in mean skin temperature between the caffeine and control treatment at baseline.

Mean skin temperature started to increase after caffeine consumption, but not in the control treatment, the differences becoming statistically significant after about 90 min. The within-subject variability in mean skin temperature however, was large (mean value about 0.5 degree C after caffeine consumption, 0.2 degree C during control treatment).

The abdominal wall temperature rose after caffeine ingestion, however, the difference between caffeine and control treatment was not significant.

The internal temperature after caffeine ingestion rose faster compared to the control treatment, resulting in a significant difference after 120 min. The within-subject variability of the internal temperature was low (mean value 0.1 degree C during both treatments).

Changes in energy expenditure were not correlated with changes in mean skin temperature (compared to basal measurements).

An increase in skin temperature of 1 degree C caused an increase in energy expenditure of 0.095 kJ/min/m2. Application of this prediction formula to the resting conditions overestimated the RMR with 0.28±0.40 kJ/min (P<0.05).

The corrected RMR as well as the difference between the corrected and the measured RMR was neither correlated with the caffeine-induced themogenesis nor with the variation in caffeine-induced thermogenesis.

Author Conclusion:

As stated by the author in body of report:

  • “The results of this study show that the curves of skin temperature and internal temperature after caffeine-induced thermogenesis differ from the curve of energy expenditure measured by indirect calorimetry.”
  • “After ingestion of caffeine, metabolic rate increased immediately with 0.2±0.2 kJ/min, and remained elevated for at least 3 h. Total caffeine-induced thermogenesis was 54±36 kJ/180 min, which was an increase over the RMR of 7±4%."
  • The rise in metabolic rate is about half of the rise found in a recent study (Tagliabue et al (1994) [and may] be due to the different form in which the coffee was served [and] with lower amount of caffeine in the present study (200 mg compared to about 260 mg).
  • "The effect of caffeine on the internal temperature became significant 120 min after ingestion, thus was 2 h delayed compared to the metabolic rate. This delay is probably due to thermoregulative mechanisms, and is also found in other studies using either a meal or caffeine as a stimulus.” [yet, there was no] statistically significant relationship between internal temperature and RMR under basal conditions.”
  • “From the relationship between mean energy expenditure and mean skin temperature found in this study, it can be calculated that an increase in 1 degree C in skin temperature coincides with an increase in metabolic rate of 0.095 kJ/min/m2 or about 5.70 kJ/h/m2. This demonstrates the limited value of skin temperature in predicting energy expenditure."
  • “In conclusion, after caffeine ingestion, mean energy expenditure and mean skin temperature were positively related. However, both skin temperature and internal temperature showed a delayed increase and their changes were not correlated with the change in metabolic rate. Changes in skin temperature can therefore not be used as a valid measure of changes in energy expenditure in short-term studies.”
Funding Source:
University/Hospital: Wageningen Agricultural University
Reviewer Comments:

Strengths

  • Good description of IC and accuracy.
  • Good description of methodology used in study.

Limitations

  • Small sample size of young men; volunteers (selection bias); lack of relationship between internal temperature and RMR under basal conditions may be due to type 2 error.
  • Generalizability: Results may not be generalized to nonobese individuals, older individuals and to females;gender differences might have been responsible for the slight difference in the relationship between energy expenditure and skin temperature in this study.
  • Did not provide information on the subjects’ ages or ethnicity (however researchers indicated the sample was homogeneous).
  • Ethnicity may be a confounder (?) as results contradicted results of study with Pima Indians.
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
  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
  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
  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
  4. Is the intervention or procedure feasible? (NA for some epidemiological studies) Yes
 
Validity Questions
  1. Was the research question clearly stated? 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
  1.1. 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
  1.2. Was (were) the outcome(s) [dependent variable(s)] clearly indicated? N/A
  1.3. Were the target population and setting specified? 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. 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
  2.1. 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
  2.2. Were criteria applied equally to all study groups? N/A
  2.3. Were health, demographics, and other characteristics of subjects described? N/A
  2.3. 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
  2.4. Were the subjects/patients a representative sample of the relevant population? N/A
  3. Were study groups comparable? 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
  3.1. 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
  3.2. 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
  3.3. 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
  3.4. 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
  3.5. 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
  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. Was method of handling withdrawals described? No
  4.1. Were follow-up methods described and the same for all groups? N/A
  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
  4.2. 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
  4.3. Were all enrolled subjects/patients (in the original sample) accounted for? N/A
  4.4. Were reasons for withdrawals similar across groups? N/A
  4.4. 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
  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? Yes
5. Was blinding used to prevent introduction of bias? Yes
  5.1. In intervention study, were subjects, clinicians/practitioners, and investigators blinded to treatment group, as appropriate? 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
  5.2. 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
  5.3. 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
  5.4. 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
  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. 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
  6.1. 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
  6.2. 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
  6.3. 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
  6.4. 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
  6.5. Were co-interventions (e.g., ancillary treatments, other therapies) described? N/A
  6.6. Were extra or unplanned treatments 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
  6.7. 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
  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? No
7. Were outcomes clearly defined and the measurements valid and reliable? No
  7.1. Were primary and secondary endpoints described and relevant to the question? N/A
  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
  7.2. 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
  7.3. 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
  7.4. 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
  7.5. 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
  7.6. Were other factors accounted for (measured) that could affect outcomes? N/A
  7.7. Were the measurements conducted consistently across groups? 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. 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
  8.1. 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
  8.2. 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
  8.3. 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
  8.4. 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
  8.5. 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
  8.6. 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
  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. Are conclusions supported by results with biases and limitations taken into consideration? Yes
  9.1. Is there a discussion of findings? N/A
  9.1. Is there a discussion of findings? N/A
  9.2. Are biases and study limitations identified and discussed? 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. Is bias due to study's funding or sponsorship unlikely? Yes
  10.1. Were sources of funding and investigators' affiliations described? 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
  10.2. Was the study free from apparent conflict of interest? N/A