AWM: Eating Frequency and Patterns (2013)

Study Design:
- Click here for explanation of classification scheme.
Quality Rating:
Research Purpose:
  • To examine differences in the energy density (ED; in energy content per gram of food) of diets between breakfast consumers and non-consumers
  • In breakfast reporters, to examine the association of ED of breakfast foods with ED of non-breakfast foods, diet quality and body mass index (BMI).
Inclusion Criteria:

All respondents were aged 20 years or more.

Exclusion Criteria:
  • Unavailable recalls: N=1,812
  • Incomplete and unreliable recalls: N=89
  • Recalls of pregnant and lactating women: N=843)
  • Recalls from proxies: N=270
  • Reports of zero calories: N=2.
Description of Study Protocol:


  • Data were taken from the continuous National Health and Nutrition Examination Surveys (NHANES) 1999–2000, 2001–2002 and 2003–2004. Dietary data from the three continuous National Health and Nutrition Examination Surveys (1999–2004) were combined to determine the ED of foods and nutritive beverages and the ED of foods only.
  • Each survey was a stratified, multi-stage, national probability sample of the civilian non-institutionalized population of the United States.


Cross-sectional study. 

Statistical Analysis 

  • Multivariate regression methods were used to examine the differences in the ED of foods reported by breakfast reporters and non-reporters
  • Linear and logistic regression methods, adjusted for covariates, were used to examine the associations of breakfast reporting or breakfast ED with 24-hour ED, non-breakfast ED, diet quality and BMI.
Data Collection Summary:

Timing of Measurements 

  • The survey procedures consisted of a household interview and a health examination, measures of weight and height and a 24-hour dietary recall
  • Definition of breakfast: During the 24-hour dietary recall, respondents were asked to name each eating episode reported
  • Breakfast reporter: Respondents mentioned eating occasions named as breakfast, desayuno or almuerzo.

Dependent Variables

  • ED was assessed with the use of two different measures:
    • The ED (in kcal per gram) of foods and nutritive beverages included milk and 100% fruit and vegetable juices
    • The ED of foods only excluded all beverages and anything added to beverages
  • 24-hour ED and energy intake (EI), breakfast EI, non-breakfast ED and EI, dietary total and saturated fat intake, mentioned all five food groups, BMI and a number of recently identified at-risk micronutrients

Independent Variables 

  • Mentioned breakfast in the recall (breakfast consumers vs. non-consumers)
  • ED of all breakfast foods and nutritive beverages vs. ED of all breakfast foods only.

Control Variables 

Sociodemographic and lifestyle variables.


Description of Actual Data Sample:
  • Initial N: 15,332 were eligible for inclusion
  • Attrition (final N): 12,316 men and women, indicating 19.7% dropout rate
  • Location: US.
Summary of Results:

Key Findings 

  • The 24-hour energy intake of breakfast reporters (2,278+15kcal) was higher than non-reporters (1,998+27), P<0.001
  • The ED of 24-hour dietary intake was lower among breakfast reporters (1.68+0.013) than among non-reporters (1.83+0.02), P<0.001
  •  In women, breakfast reporters had lower BMI than did non-reporters (27.9±0.2 compared with 29.4±0.4; P=0.001)
  •  With increasing breakfast ED, non-breakfast ED and fat intake increased, but micronutrient intake and the likelihood of mention of all five food groups declined
  • BMI increased with increasing breakfast ED in men (P=0.001)  but with increasing non-breakfast ED in women (P≤0.001)
  • The five most frequently reported food group combinations:
    • Dairy and grain
    • Grain only
    • Dairy, fruit and grain
    • Grain and meat or alternate
    • Fruit and grain
  • The highest mean ED of each type was associated with the breakfast that excluded foods from all the major food groups.
Author Conclusion:

The results support recommendations to encourage breakfast consumption and suggest that the ED of breakfast was associated with diet quality, overall diet ED and body weight.

Funding Source:
Quaker and Tropicana
Food Company:
The Breakfast Research Institute and Rippe Lifestyle Institute
Foundation associated with industry:
In-Kind support reported by Industry: Yes
Reviewer Comments:


  • This study used a nationally representative sample
  • Since data were taken from national surveys, all measures were based on standard, valid and reliable data collection procedures. Also, the measures were conducted consistently across groups
  • Blinding was assumed because dietary data were not collected by the same group of researchers who wrote this article.


  • It was unclear whether all enrolled subjects were accounted for
  • Health, demographics and other characteristics of subjects were not described
  • It was uncertain whether groups were comparable on important confounding factors
  • This study was not completely free from conflict of interest.


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? 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? N/A
  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) 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? Yes
  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? 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? Yes
  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.) Yes
  5.3. In cohort study or cross-sectional study, were measurements of outcomes and risk factors blinded? Yes
  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? 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? 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? 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? 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)? Yes
  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? Yes
  9.2. Are biases and study limitations identified and discussed? Yes
10. Is bias due to study's funding or sponsorship unlikely? No
  10.1. Were sources of funding and investigators' affiliations described? Yes
  10.2. Was the study free from apparent conflict of interest? No