Adult Weight Management

AWM: Eating Frequency and Patterns (2006)

Westerterp-Plantenga MS, Kovacs EMR, Melanson KJ. Habitual meal frequency and energy intake regulation in partially temporally isolated men. Intl J Obes 2002; 26: 102-110.
Study Design:
Randomized Controlled Trial
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Quality Rating:
Positive POSITIVE: See Quality Criteria Checklist below.
Research Purpose:

Assessment of a possible relationship between habitual as well as manipulated meal frequency, blood glucose pattern, micronutrient and energy intake, and energy intake regulation in partially temporally isolated men.

Inclusion Criteria:
Healthy, non-smoking, normal weight males.
Exclusion Criteria:

None stated.

Description of Study Protocol:

Recruitment university newspaper

Design randomized, cross-over, within subjects trial.  On 2 separate days after a 10 hour overnight fast, subjects were given a different preload (iso-energetic, iso-caloric high fat or high carbohydrate (CHO)) upon their first meal request, then had blood glucose, hunger, satiety, taste perception, and ad lib food intake measured for 8 hours or until clot formation prohibited further blood glucose monitoring (in 2 of 40 tests). Ad lib food and water were available and subjects were deprived of time cues.

Blinding used  Preload was delivered as a lemon-flavoured drink to mask differences between high-CHO and high-fat drinks.

Intervention NA

Statistical Analysis  Repeated measures ANOVA, stepwise regression, and chi-square.

Data Collection Summary:

Timing of Measurements 2 conditions (high fat or high CHO) were tested on 2 different days, separated by at least 1 week.

Dependent Variables

Blood glucose (BG): An 18-gauge, 15 mm angiocath was place in a lower arm or antecubital vein of the non-dominant arm. A heparinized catheter was used to continuously draw blood.  Very specific details on glucose monitoring protocol are included in paper.

Hunger, satiety, taste perception: self-rating on 100 mm VAS, anchored with 'not at all' and 'very much' were taken before and after each eating episode.

Food intake during testing periods: ad lib food and water was available.  Differences in weight between foods available and foods consumed were used to determine total energy and macronutrients consumed.

Habitual food intake: 3 day food record before testing periods.

Hedonic rating (pre-testing) of preloads and ad lib food: 100 mm Visual Analog Scales was used to determine that preloads and ad lib foods were hedonically equal and pleasing to subjects.

Independent Variables

Isocaloric, iso-volumetric 1 MJ preload - either high CHO (100% CHO) or high fat (13.6% CHO/2.3% protein/84.1% fat).

Control Variables  none stated

Description of Actual Data Sample:

Initial N:  20 men       

Attrition (final N):  20

Age: 23.3±4.0 years

Ethnicity: not stated

Other relevant demographics: Subjects were tested for restrained eating (Herman & Polivy and Three-Factor Eating Questionnaire) and all scored in the normal range but the authors do not specifically state this as an exclusionary criteria.

Anthropometrics (e.g., were groups same or different on important measures) BMI = 22.8±1.9 kg/m²

Location: Netherlands

Summary of Results:

BG patterns:

  • On 26 of the 40 test days, a transient post-absorptive BG decline occurred after the first 30 minutes of BG monitoring.  Of those 26 declines, 92% (24) were associated with a meal request.
  • After the first meal (preload) a postprandial dynamic decline occurred, 32 (80%) of those declines were associated with a meal request.
  • After the 2nd (ad lib) meal, 20 postprandial transient declines took place, of which 17 (85%) were associated with a meal request.

Preload effects:

  • 1st intermeal interval was less for CHO preload compared to fat preload (62 vs 121 min, p>0.001)
  • both intermeal intervals were related to change in satiety over time (r²=0.54;p<.01)
  • manipulated meal frequency was higher on CHO preload day (p<.05)
  • manipulated meal frequency was positively related to the total number of transient and dynamic declines on each test day (high-CHO: r²=0.76; high fat: r²=0.74, p<0.0001); macronutrient composition did not differ significantly
  • total and % CHO intake was higher and fat intake lower on high-CHO preload days (p<0.05).

Habitual meal-frequency effects:

  • habitual meal frequency from food records was positively related to manipulated meal frequency on test days (r²=0.86, p<0.0001)
  • % of energy from CHO or fat explained the variation in habitual meal frequency (r²=0.84, p<0.0001)
  • sweetness perception and hunger suppression during preload were inversely correlated (r²=0.76, p<0.0001)
  • variation in energy intake was primarily explained by habitual meal frequency (r²=0.76, p<0.0001).

Other Findings

Reported habitual intake was lower than the total energy intake on the 2 experimental days (p<0.05), suggesting underreporting of habitual intake.

Author Conclusion:

Habitual meal frequency is of greater significance in energy intake regulation in healthy young men, with high habitual meal frequency showing lower 24 hour intake. This suggests a more accurate energy intake regulation.  Habitual meal frequency is based upon a cluster of related factors including macronutrient composition of the food, sweetness perception, hunger suppression, blood glucose declines, and baseline blood glucose levels.

Funding Source:
Hertog Jan Brewery (Netherlands)
University/Hospital: Maastricht University (Netherlands)
In-Kind support reported by Industry: Yes
Reviewer Comments:

Interesting and well-done study demonstrating that, in healthy young men, a higher habitual meal frequency would appear to demonstrate a more accurate energy intake regulation. These authors did not test to determine if a more accurate energy regulation was related to a more appropriate body weight.

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? Yes
  1.2. Was (were) the outcome(s) [dependent variable(s)] clearly indicated? Yes
  1.3. Were the target population and setting specified? Yes
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? Yes
  2.2. Were criteria applied equally to all study groups? Yes
  2.3. Were health, demographics, and other characteristics of subjects described? Yes
  2.4. Were the subjects/patients a representative sample of the relevant population? ???
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) Yes
  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? Yes
  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%.) Yes
  4.3. Were all enrolled subjects/patients (in the original sample) accounted for? Yes
  4.4. Were reasons for withdrawals similar across groups? Yes
  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
  5.1. In intervention study, were subjects, clinicians/practitioners, and investigators blinded to treatment group, as appropriate? Yes
  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.) Yes
  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? Yes
  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? Yes
  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? Yes
  7.2. Were nutrition measures appropriate to question and outcomes of concern? Yes
  7.3. Was the period of follow-up long enough for important outcome(s) to occur? Yes
  7.4. Were the observations and measurements based on standard, valid, and reliable data collection instruments/tests/procedures? Yes
  7.5. Was the measurement of effect at an appropriate level of precision? Yes
  7.6. Were other factors accounted for (measured) that could affect outcomes? ???
  7.7. Were the measurements conducted consistently across groups? 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? Yes
  8.2. Were correct statistical tests used and assumptions of test not violated? Yes
  8.3. Were statistics reported with levels of significance and/or confidence intervals? Yes
  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? Yes
  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? Yes
  9.2. Are biases and study limitations identified and discussed? Yes
10. Is bias due to study's funding or sponsorship unlikely? Yes
  10.1. Were sources of funding and investigators' affiliations described? Yes
  10.2. Was the study free from apparent conflict of interest? Yes