AWM: Eating Frequency and Patterns (2013)

Study Design:
- Click here for explanation of classification scheme.
Quality Rating:
Research Purpose:
To study the effect of the energy content of breakfast on dietary and metabolic patterns.
Inclusion Criteria:
None stated.
Exclusion Criteria:
None stated.
Description of Study Protocol:

Recruitment Not stated

Design  Subjects were assigned either a low energy, moderate fat breakfast (LE breakfast; 100 kcal; 34.4% fat) ) or a high energy, low fat breakfast (HE breakfast; 700 kcal; 24.6% fat) for two 2 week periods in a crossover design.

During the 2 week periods the subjects ate their assigned breakfast at the metabolic unit between 7 and 9 am, after which they returned to their normal routine and recorded their intake for the remainder of the day.

The two experimental periods were separated by 4 weeks of ad lib feeding. Subjects kept food records for the 4 weeks. 

On the 15th day of each experimental period, after an overnight fast and consuming the assigned breakfast, the metabolic test was performed and blood was drawn by catheter while they remained at rest for the remainder of the day.

Blinding used (if applicable)  Subjects were not blinded to composition of breakfast.       

Intervention (if applicable)  Low energy, moderate fat (LE) breakfast vs. high energy, low fat (HE) breakfast

Statistical Analysis Comparisons between periods were made using the Mann-Whitney test.

Data Collection Summary:

Timing of Measurements:  2 2-week periods separated by a 4 week period of ad lib feeding

Dependent Variables

  • Total energy intake: food records
  • Breakdown of intake within the day: food records
  • Hunger ratings: visual analog scale
  • Distribution of energy between nutrients: food records
  • Serum variables for glucose, insulin, total cholesterol, LDL-cholesterol, free fatty acids (FFA)
  • Energy expenditure: indirect calorimetry

Independent Variables  LE or HE breakfast composition

Control Variables  none stated

Description of Actual Data Sample:

Initial N: 10 males

Attrition (final N): 10

Age: 28 ± 2 years

Ethnicity: not stated

Other relevant demographics:  weight - 69.7 ± 3.0 kg

Anthropometrics BMI 22.2 ±0.5

Location: France

Summary of Results:

Energy intake (kJ) across test days and free diet

LE breakfast

free diet     HE breakfast
total daily intake     10254±1789 10604±1889 11737±1141
energy from breakfast 464±8 1923±598 2964±8
energy from morning snack 577±497     96±84 117±117
energy from lunch 4548±694 4138±1258 4080±711
energy from afternoon snack 451±309 506±268 602±376
energy from dinner 4055±1020 3846±773 3766±598
energy from evening snack 159±213 100±130 213±272


No weight change was observed across the test periods.  Excluding breakfast, the macronutrient composition of intake remained the same in the 2 conditions.

  • Subjects increased energy intake during other meals (p=.0051) when consuming LE breakfast.
  • Percent intake from CHO was increased during HE breakfast condition (p<.05).
  • There was a difference in hunger rating for LE breakfast ( p<.05) only at 10 am, resulting in more snacks.
  • HE breakfast resulted in high glycemic response in the AM, but FFA increased after LE breakfast (Ps<.05).
  • After HE breakfast, fasting serum concentration of triacylglycerols was higher than basal values and HDL-cholesterol concentration was lower than LE breakfast (Ps<.05). 
  • HE breakfast induced strong decrease in fat oxidation throughout the day (p<.05).
  • The HE breakfast resulted in increases in triacylglycerol and HDL-cholesterol, but not out of normal ranges.
Author Conclusion:
Results of the study do not support the current advice to consume more energy at breakfast.
Funding Source:
University/Hospital: St. Louis University School of Medicine
Reviewer Comments:
Although this is a complex and sophisticated design, this study has weaknesses.  The authors cite other literature that a 'usual' breakfast is about 17% of daily intake, but their LE condition was 5% of intake, while their HE condition was 27% of intake.  Thus, they failed to test the type of breakfast most often consumed.  The authors appear to be drawing conclusions from a metabolic, rather than a weight management, perspective. The presentation of the information in the paper is confusing and much of what is presented is not pertinent to the question.
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) ???
  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) ???
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? No
  2.2. Were criteria applied equally to all study groups? ???
  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.) Yes
  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? No
  5.1. In intervention study, were subjects, clinicians/practitioners, and investigators blinded to treatment group, as appropriate? No
  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? Yes
  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? ???
  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? No
  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