AWM: Eating Frequency and Patterns (2013)

Study Design:
- Click here for explanation of classification scheme.
Quality Rating:
Research Purpose:
To evaluate the effects of eating breakfast on changes in body weight, body composition, reesting metabolic rate, macronutient intake, psychological adjustment, and eating behaviors.
Inclusion Criteria:
None stated.
Exclusion Criteria:
  • self-reported history of any serious medical problem (e.g., diabetes, cancer)
  • reporting losing > 4.5 kg in last month or > 9 kg in last 6 months
  • reporting using cigarettes or nicotine gum
  • reporting using any medication that would affect resting metabolic rate
Description of Study Protocol:

Recruitment Newspaper article asking for volunteers to participate in weight loss research


initial telephone interview to screen out exclusions

orientation: taught to keep a behavioral eating diary coding their meals by using a 6 food group exhange program and instructed to keep a 2-wk food diary following their typical eating patterns

Subjects were stratified by their breakfast eating habits before the study.  Those reporting eating breakfast > 4 times/week were in the breakfast eater strata, while those reporting eating breakfast < 3 times/week were in the non-breakfast eater strata.  Subjects were then randomly assigned (approximately equal numbers) to each of the 2 experimental conditions (breakfast or no breakfast).

Measures of body weight, body composition, energy expenditure, BP, lipids, and questionnaire regarding intake, dietary restraint, binging, body cathexis, and physical symptoms were also completed.

At 6 months after the beginning of the program, participants returned to be weighed and retested on several dependent measures.

Blinding used (if applicable) NA

Intervention (if applicable)

2 1200 kcal/d weight reduction programs were used - one divided into 2 meals/d (no breakfast group) and the other into 3 meals/d (breakfast group).  Both patterns consisted of 50-55% CHO, 15-20% protein, and 25-30% fat. 

12 week behavior modification program consisting of a 90-minute group meeting weekly.  Basic approach was problem solving and skill training.  To individualize intervention, participants received computer-generated feedback from eating diaries. Contingeny contracts were used to enhance session attendance and participation in follow-up.

Statistical Analysis Repeated measures ANOVA with subject strata (breakfast-eater vs non-breakfast-eater history) and experimental treatments as between subjects factors.  Repeated measures factor was time (2 levels - baseline and post-treatment).

Data Collection Summary:

Timing of Measurements baseline, then weekly, and at end of treatment

Dependent Variables

body weight: baseline, weekly, follow-up

body composition: underwater weighing at beginning and end of study

energy expenditure: RMR with indirect calorimetry, before and after weight loss

blood pressure: at baseline and post-treatment

lipids: baseline and after 12 weeks of treatment

self-monitoring of eating behavior: behavioral diary for 2 week baseline and 12 weeks of intervention.  Heirarchical cluser analysies was used on baseline data to derive 20 cluster scores measuring different aspects of eating behavior.

DIET questionnaire:  baseline and posttreatment

3 factor eating questionnaire: baseline and posttreatment

SCL-90:  baseline and posttreatment

Hawkins binge scale:  baseline and posttreatment

body cathexis scale:  baseline and posttreatment

56-item physical symptoms checklist:  baseline and posttreatment

Independent Variables  Assignment to breakfast or no-breakfast experimental conditions.

Control Variables none listed

Description of Actual Data Sample:

Initial N: 52 moderately obese women

Attrition (final N):  7 (4 from no-breakfast, 3 from breakfast) dropped before end of intervention.32 of the 46 (70%) subjects completing the intervention returned for the 6 month follow-up.

Age: 18-55 years

Ethnicity: not reported

Other relevant demographics: BMI = 30.6 +/- 0.5

Anthropometrics not reported

Location: Vanderbilt University Medical Center in Nashville TN

Summary of Results:

Mean weight loss by strata and treatment
Breakfast Eaters Breakfast Skippers
Breakfast 6.2+/-3.3 kg 7.7+/-3.3 kg
No Breakfast 8.9+/-4.2 kg     6.0+/-3.9 kg

Main effect for weight loss across time (P<0.001).

Interaction effect with subjects assigned to a treatment different from their pre-treatment breakfast habits losing marginally more weight (P<0.06).

There are a multitude of statistical tests reported.  The ones of interest break down into 2 groups: main effects for treatment and interaction effects for pre-study breakfast habits and treatment:

Main effects for breakfast treatment (all Ps<0.001) with the breakfast treatment group showing a greater reduction in :

  • energy and fat from impulsive snacking
  • meal size
  • energy and fat at social meals
  • frequency of very large meals
  • impulsive snacking

Interaction effect with breakfast skippers assigned to the breakfast treatment (all Ps<0.001) showing a greater reduction in:

  • impulsive snacking
  • meal size
  • uncontrolled eating
  • high energy and fat intake at work


Author Conclusion:
"We recommend that individuals attempting a weight-loss program incude a breakfast that is low in fat and high in carbohydrates as part of their weight-loss regimen.  People who regularly skip breakfast may benefit from the addition of breakfast to their eating plan.  Eating breakfast also may help protect the individual from unplanned snacking later in the day and can help reduce the amount of calories and fats in these snacks when they do occur.  Although subjects who initially ate breakfast lost more weight in the no-breakfast gorup, we do not believe that these individuals should be advised to stop eating breakfast because eating breakfast is associated with a reduction in total fat intake and a reduced impact of impulsive eating."
Funding Source:
University/Hospital: Vanderbelt University
Reviewer Comments:
Interesting and well-done but overly ambitious project.  There were so many statistical tests reported that it was difficult to sift through and find the interesting results.  The large number of statistical tests is also problematic from a power standpoint and decreases the enthusiasm for the study.  However, the study still provides additional evidence that consumption of breakfast leads to better intake throughout the day.
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? No
  2.4. Were the subjects/patients a representative sample of the relevant population? Yes
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? ???
  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? 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? Yes
  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? Yes
  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? No
  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)? ???
  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