- To examine the extent to which adaptive responses of TEE, resting energy expenditure (REE) and substrate oxidation in relation to changes in dietary energy intake.
- To test the hypotheses that adaptive response of energy expenditure to energy imbalances are greater during negative enrgy balance than during positive energy balance and older men have attenuated energy expenditure responses to energy imbalances compared to younger men.
- Steady state:
- Mean post-prandial TEF: The avg increment in metabolic rate above the fasting level for each measurement in each subjectl
- Maintenance Energy expenditure (MAT): The avg of all fasting and fed-state measurements
- Metabolizable energy (ME): Measured gross energy intakes and energy losses in urine and stools.
Understand and give written consent
Healthy as judged by a physical examination, urnialysis, and CBC
- No recent illnesses or hx endocrinopathy.
- Refusal to consent
- Not meeting inclusion criteria.
- Phase 1: 10 days where subjects’ energy intake for body weight maintenance were determined
- Phase 2: 21 days where subjects consumed approximately 984 kcal/d MORE than in Phase 1 (overfeeding study) or 768 kcal/d LESS (underfeeding) studies.
- Ht measured? Yes
- Wt measured? Yes
- Fat-free mass measured? Yes, doubly-labelled water
- Monitored heart rate? Not specified
- Body temperature? No
- Medications administered? No
Resting energy expenditure
- IC type: Tissot spirometer and analyzed by Beckman Instruments Or a Deltatrac, SensoMedics; No differences between systems in repeated tests of accuracy and precision
- Equipment of Calibration: Cited other protocol-1991, 1992 study
- Coefficient of variation using std gases: Stated testing reported in another journal article
- Rest before measure (state length of time rested if available): 30 mins
- Measurement length: 30 min increments
- Steady state: Instructed to relax, avoid hyperventilation, fidgeting and sleepig during measures
- Fasting length: Fasted, 10-13 hr
- Exercise restrictions XX hr prior to test? sampling included sedentary workers or full-time students
- Room temp: not specified
- No. of measures within the measurement period: baseline, and continuous for 240 mins after eating 25% of total estimated energy needs
- Were some measures eliminated? Some 30 measures were missed
- Were a set of measurements averaged? Yes, 30 min periods were averaged
- Coefficient of variation in subjects measures? No
- Training of measurer? Likely
- Subject training of measuring process? Not specified
Consumed 25% of their estimated total energy requirements; i.e., daily intake of protein, fat & CHO (excluding any coffee or tea); 30 minutes after breakfast started, RMR measures were begun and continued 20 mins out of every 30 minutes]. InPhase 1, diet was a typical high protein American diet; ~1.5 g/kg body wt, 55% CHO and 45% fat.
Outcome(s) and other measures
- Measured REE [(VO2 l/min), VCO2 (l/min; ml/kg/min), RQ, ventilation (l/min)].
- TEE, TEF, self-reported physical activity
- Independent variables of weight, height, age, BMI, fat-free mass, % body fat.
Blinding used: No
Younger aged males
- N=17 healthy, young males
- Mean age, y: ~23 y
- One subject was not included in data analysis due to RMR data that was very unusual.
Older aged males
- N=19 males
- Mean age, y: 68.
- Values are mean±SD and mean ±SEM; ANOVA and student’s paried t-test; Regresion analysis; P<0.05 were significant.
Younger Men (n=15)
|Overfeeding (Mean±SD)||Underfeeding (Mean±SD)|
Fat-free body mass
Body fat, %
|Older Men (n=19)||Overfeeding(Mean±SD)||Underfeeding(Mean±SD)|
Fat-free body mass
Body fat, %
- Number of measurement intervals: 2-baseline and continuous 240 min measure
- Length of measurements: 30, 240 mins
- Steady state: not specified
There were signifincat differences between young and elderly men in age (P<0.001), BMI (P<0.05), body fat mass(P<0.001) and reported activity >5 X REE (P<0.05).
RMR RESULTS AND TEST MEAL
All subjects consumed exactly 25% of estimated TEE and there was substantial individual variability in the size of the test meal and a significantly lower mean intake in older men compared to younger men (P<0.01).
To normalize data between subjects, increases in EE above initial fasting baseline are expressed as % of ingested energy.
There was no significant difference in TEF between young and older subjects but the timing of the peak post-prandial energy expenditure was significantly delayed in the older subjects compared to the younger one (P<0.05).
THERMIC EFFECT OF THE MEAL TEST
For young and old subjects combined, there was a significant difference between overfeeding and underfeeding in all the measures of energy expenditure and fast RQ.
The sum of TEE changes with overfeeding and underfeeding was equivalent to 19.1% of the combined change in energy intake between both studies; while the sum of change in REE accounted for 6.3%. There was a trend (nonsignificant) for greater changes in energy expenditure with underfeeding than with overfeeding.
Post-prandial energy expenditure (corrected for baseline expenditure and expressed as % of ingested energy)
[i.e., average increment in metabolic rate above the fasting level/ ingested energy times 100]
|Percentage ingested energy above baseline (kcal/min)|
(Estimates taken from Figure 1)
As stated by the author in body of report
“We have used data collected in separate but comparable overfeeding and underfeeding studies to examine the magnitude total energy expenditure changes, energy expenditure components and RQ in response to energy imbalance and these changes are more anticipated on body weight change. ”
“Changes in REE and TEF were smaller than the changes in TEE, with the REE accounting for 6.3% of combined change in energy intake (i.e., over and under feeding).”
“No significant differences were observed between the magnitude of TEE or REE responses to underfeeding and overfeeding; however, the mean changes in TEE and REE were greater with underfeeding than with overfeeding . . . [and] these changes were in response to a smaller degree of energy restriction during underfeeding than energy surplus.”
“The TEE response to altered energy balance is considerably larger than the REE response [and] we found no significant effect of age on the change in TEE with energy imbalance; there was no significant effect of age on measured energy deposition during overfeeding or underfeeding..”
“Post-prandial peak of energy expenditure is significantly delayed in older subjects and aging is associated with some dysregulation of energy expenditure responsiveness to energy imbalance, the net effect is small and hard to detect in short-term studies even though, cumulatively, such changes could have a major impact on long-term energy regulation and body fat mass.
- “Research allows were allowed to pursue a normal lifestyle and continue usual activities so generalizability greater than if in room calorimetry”
- RMR measured continuously using a standardized protocol
- Controlled dietary intake through assigned foods.
- Convenience sampling bias
- Ethnicity of subjects not reported
- An intervening variable is reflected in using two types of calorimetry: calibrated Tissot spirometer vs. Deltratrac; Report alcohol burning precision accuracy
- These are important variables on REE measurement accuracy: did not report steady state monitoring over 20 minutes out of every 30 minutes. Some difficulties may have occurred and related to statement “some 30 min measures missing and the prior mean measure was inserted.” Also discussed fidgeting and hyperventilation monitoring.
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?||Yes|
|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?||Yes|
|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|