AWM: Eating Frequency and Patterns (2013)

Study Design:
- Click here for explanation of classification scheme.
Quality Rating:
Research Purpose:
To examine the relationship between eating patterns and obesity.
Inclusion Criteria:

Data was from Seasonal Variation of Blood Cholesterol Study (SEASONS).  Inclusion criteria for that study included:residents of Worcester County, MA; aged 20-70 years; had telephone service; and were:

  • not taking cholesterol-lowering medication
  • not currently on lipid-lowering medications;
  • free from possible causes of secondary hypercholesterolemia
  • not working night shift
  •  free from chronic illness.
Exclusion Criteria:

138 subjects in the SEASONS cohort who completed fewer than 10 24-hour recalls and 4 subjects that were working night shifts were excluded.

Description of Study Protocol:

Recruitment Recruitment was initially done within the HMO but a recruiter was also used specifically to recruit minority participants who were not members of the HMO. The resulting sample was 87.7% white.

Design Cross-sectional design using 3 24-hour recalls and body weight collected over 5 time periods and averaged.

Blinding used  NA

Intervention  NA

Statistical Analysis Logistic regression with the following Control Variables:

  • age
  • gender
  • physical activity
  • education level
  • total energy intake
Data Collection Summary:

Timing of Measurements 5 measurements equally spaced across 1 year

Dependent Variables

BMI: normal < 25; overweight > 25; obese > 30.

Independent Variables

From 24-hour recalls collected at 5 equally spaced time points over a 1-year period:

  • number of eating episodes/day
  • regular breakfast eater?
  • 1st time of eating after awakening
  • interval between the last eating episode and bed-time
  • amount of time between waking and largest meal of the day
  • frequency of eating meals away from  home

Control Variables

  • age
  • gender
  • physical activity
  • education level
  • total energy intake
Description of Actual Data Sample:

Initial N: 641        

Attrition (final N):  499.  142 were excluded because of insufficient numbers of dietary recalls. Comparison found no differences in terms of gender, education or BMI but included subjects tended to be older, white, nonsmoking, married, and to have white-collar jobs more than those excluded.

Age: Distributed from 20-70 with ~75% between 41 and 70.

Ethnicity: 87.7% white

Other relevant demographics: Education, smoking status, occupational category.

Anthropometrics    Men: 48% overweight, 27% obese

                               Women: 33% overweight, 20% obese

Location: Worcester County, MA

Summary of Results:

Descriptives for entire sample:

  • participants ate 3.92 times daily
  • mean energy intake was 2259 ±540 for men and 1641±363 kcal for women
  • 3.6% were classified as breakfast skippers
  • mean of 29.7% of meals were eaten away from home
    • 18.9% breakfast
    •  53.5% lunch
    •  19.6& dinner


  • Higher education was associated with lower risk of obesity (p <0.001), with post-high school OR = .70 and > bachelors' degree OR =.36 (compared to  < high school).
  • Physical activity was inversely related to obesity (p for trend <0.041), with the highest quartile (17.7 MET-hours/day) OR=.56 compared to quartile 1 (5.6 MET-hours/day).
  • Age, race/ethnicity, gender, smoking status, occupational status, and total energy intake were not associated with risk of obesity.
  • Number of eating episodes was inversely associated with the risk of obesity (95% CI: 0.33, 0.91)., with > 4 episodes/day having a 45% lower risk of obesity, compared to  < 3 episodes/day
  • Skipping breakfast (75% of days measured by the 24-hour recall) was associated with a higher risk of obesity (OR=4.5; 95% CI: 1.57, 12.90).
Author Conclusion:

Eating patterns are associated with obesity even after controlling for total energy intake and physical activity. A greater number of eating episodes each day was associated with a lower risk of obesity; skipping breakfast was associated with increased prevalence of obesity; greater frequency of eating breakfast or dinner away from home was associated with increased prevalence of obesity.

The authors caution that their results should not be considered causal as current diet might not be representative of past diet.

Funding Source:
Government: NHLBI
Reviewer Comments:
Very well-done analyses with interesting findings.  The authors' presentation of how their results fit into the extant literature is thoughtful.  A major strength is the use of a large number of 24-hour recalls spread out over a year's time, which increases the stability of the dietary intake data. Similarly, they have multiple physical activity recalls.  A weakness may be the large number (142) of those subjects that did not complete 10 24-hour recalls.  However, the authors compared those subjects with the 499 in the analysis on gender, educational level, and BMI and found no differences. Another weakness may be that the sample used was 87.7% white, despite their attempts to recruit minority participants outside the system.  This may decrease the generalizability of the findings.
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? ???
  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? N/A
  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? 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? 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? 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? 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? 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? 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? 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