AWM: Eating Frequency and Patterns (2013)

Study Design:
- Click here for explanation of classification scheme.
Quality Rating:
Research Purpose:
To examine the relationship between feeding pattern and BMI in free-living humans, and assess whether this relationship is dependent on the validity of recorded dietary intake.
Inclusion Criteria:
Not reported - the authors state that methods were reported earlier (Summerbell, 1995;49:33-41).
Exclusion Criteria:
Not stated.
Description of Study Protocol:

Recruitment Not stated.

Design 7-day weighed records and BMI were gathered from 4 age groups.  3 age groups used in the current study had been gathered previously:  88 elderly (24 M, 64 F; 65-91 years); 44 middle-aged (6 M, 34 F; 39-59 years); and 59 working age (29M, 30 F; 17-60 years).  33 adolescents (12 M, 21 F; 13-14 years) were gathered in the current study.  Subjects were instructed in recording their dietary intake.  Intake was divided into 6 feeding periods, with the first feeding occasion classified as breakfast.  A feeding period was defined as the consumption of any food or drink which provided energy.  2 consecutive feeding periods were considered separate if the time interval between them was greater or equal to 1 hour. The validity of the 7-day records was assessed by calculating the mean physical activity level (PAL=reported energy intake/estimated basal metabolic rate(BMR)) for each subject where BMR was calucated using age, sex, weight and height (Schofield, Schofield & James, 1985).  For this study values < 1.10 were considered invalid (underreported).

Blinding used (if applicable) NA

Intervention (if applicable) NA

Statistical Analysis One-way ANOVA, Scheffe's multiple comparison tests, correlation coefficients, linear regression equations, and un-paired t-tests.

Data Collection Summary:

Timing of Measurements Each group completed 7 days of continuous recording, weight and height were gathered concurrently and used to determine BMI.

Dependent Variables

  • feeding variability index: each feeding occasion was calculated as percent of total days intake (%MPEI); the variability index is the standard deviation around the mean of the 6 consecutive %MPEIs.**
  • feeding frequency index: calculated as the number of %MPEIs which individually exceeded 10%**
  • energy intake at breakfast: percentage of mean total daily energy intake
  • energy intake in evening:  percentage of mean total daily energy intake

** For example, a 'gorging' feeding pattern would produce a high variability index and a low frequency index, whereas a 'nibbling' feeding pattern would produce a low variability index and a high frequency index.

Independent Variables


Control Variables none stated

Description of Actual Data Sample:

Initial N: 71 M, 149 F

Attrition (final N):not stated

Age: 13-14 years:    12 M, 21 F

        17-60 years:    29 M, 30 F

        39-59 years:    6 M, 34 F

        65-91 years:    24 M, 64 F

Ethnicity: not stated

Other relevant demographics: none reported

Anthropometrics BMI, all group means (by age and gender) are under 25.O except for the middle-aged group where males = 25.0 (+/-4.2) and females = 25.2 (+/-4.6)

Location: England

Summary of Results:

Results are presented with the entire sample and with individuals excluded whose mean energy intake < a PAL of 1.10.

Entire group:

  • In adolescents-a high BMI was associated with lower energy intakes at breakfast (P<0.01), high feeding variability (P<0.05), and a low feeding frequency (P<0.05).
  • In the middle-aged group-a high BMI was associated with lower energy intakes at breakfast (P<0.05), and higher energy intakes during the evening (P<0.05).
  • Feeding pattern was not related to BMI in the working age or elderly groups.

When invalid records were removed:

  • In adolescents-absolute energy intakes at breakfast remained inversely related to BMI (P<0.05).
  • In the middle-aged group-higher energy intake during the evening remained directly related to BMI (P<0.05).
  • In the working age group-absolute energy consumed during the evening was directly related to BMI (P<0.05).


Author Conclusion:
The authors conclude that previous findings that feeding pattern is related to body weight may be due largely to invalid reporting of dietary intake.  They categorize their findings as weak evidence that feeding pattern and body weight are related, and that the habit of omitting breakfast as a dieting strategy may, in some part, be the reason omitting breakfast has so often been related to a higher body weight.  They also concluded that the amount of underreporting of intake identified in this study is similar to that found in other studies of underreporting, suggesting that a similar level of underreporting may exist in the studies reporting a relationship between feeding patterns and weight (that did not consider validity of reporting).
Funding Source:
University/Hospital: St Bartholomew's and the Royal London Hospital School of Medicine and Dentistry, Robert Gordon University, Southbank University, University of London (London UK)
Reviewer Comments:
This is a well-designed study that clearly demonstrates the effect of underreporting of dietary intake on relationships between feeding pattern and body weight.  However, two issues must be considered when putting this study into perspective.  First, weighed diet records were used.  Weighing intake has previously been shown to decrease reported intake and may have resulted in lower intake in this study.  Second, BMIs of the sample were very much in the 'normal' range of body weight.  Thus, this sample may not have contained the variability in body weight needed to reveal relationships between feeding patterns and 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) N/A
  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) N/A
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? ???
  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? ???
  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) N/A
  3.2. Were distribution of disease status, prognostic factors, and other factors (e.g., demographics) similar across study groups at baseline? ???
  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? ???
  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.) No
  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%.) ???
  4.3. Were all enrolled subjects/patients (in the original sample) accounted for? ???
  4.4. Were reasons for withdrawals similar across groups? ???
  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? 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
  5.3. 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? 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? No
  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? 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? N/A
  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