AWM: Eating Frequency and Patterns (2013)

Study Design:
- Click here for explanation of classification scheme.
Quality Rating:
Research Purpose:
To characterize meal patterns in relation to obesity in Swedish women using a simple instrument describing meal frequency, meal types, and temporal distribution.
Inclusion Criteria:

Subjects were pulled from Swedish Obese Subjects (SOS) study, which is referenced.

Exclusion Criteria:
None stated.
Description of Study Protocol:

Recruitment Two groups of women were selected from the registry of the SOS study and invited to participate. This included 100 obese women and 100 reference women.

Design Questionnaire designed to assess meal frequency, type, and time for a typical 24-hour period were mailed to obese subjects and completed by reference subjects at a health exam. (It should be noted that subjects were asked for typical, not actual, intake).  The 24-hour period was divided into 9 periods, each 2-6 hours in length.  Questionnaires were examined for differences between the obese and reference groups.

Blinding used NA

Intervention NA

Statistical Analysis Chi-sqaure, t-tests, Pearson r, and multiple linear regressions.

Data Collection Summary:

Timing of Measurements cross- sectional

Dependent Variables

All DVs were extrapolated from the questionnaire:

  • number of meals/day
  • traditional vs. non-traditional meal times
  • evening and night intake
  • proportional distribution of meals throughout the day
  • nutrient intake

Independent Variables

Weight status: Obese or normal

Control Variables

For multiple regression only: age, weight, height, number of sleeping hours

Description of Actual Data Sample:

Initial N: 100 in each group

Attrition (final N): reference women = 94 women who agreed to participate; obese women = 83 (86 women agreed to participate but 3 were excluded due to work shift).

Age: reference women = 49.6±7.2 years; obese women = 47.7±5.9 years

Ethnicity: Swedish

Other relevant demographics:

Anthropometrics  BMI: reference women = 23.8±3.1; obese women 41.0±3.4.

Location: Sweden


Summary of Results:


Study Results
variable   obese group  reference group p-value
    meals/day     6.1 5.2 <0.0001    
    light meals/breakfast 1.6 1.3 0.003
    main meals 1.4 1.2 0.008
    snack meals 2.2 1.6 0.0001
Percent intake at meal times*:
    breakfast (6.00-9.59) 21% 26% 0.002

    late-morning (10.00-.59)     

11% 11% NS
    lunch (12.00-13.59) 14%     16% NS
    afternoon (14.00-15.59) 14% 11% 0.006
    dinner  (16.00-19.59) 22% 25% NS
    evening  (20.0-23.59) 16% 11% 0.002
    night (00.00-5.59)                 2% 1% NS
Energy and macronutrient  intake:        
    energy  (kJ) 11970 9756 0.001
    protein (g) 115 90 <.0001
    % protein     16.4% 15.7% 0.0445
    fat (g)          118 91 <0.001
    % fat 37% 34% 0.0024
    carbohydrate (g) 317 268 0.0012
    % CHO 44%     46% 0.0245
    mono-disaccharides (g) 139 119 0.0285
    % mono-disaccharides 19% 20% NS
    alcohol (g) 4.0 7.7


    % alcohol 1.0 2.3 0.0001
     fiber (g) 24.6 22.7 NS

    fiber (g/M)

2.1 2.4


* time is stated in military time

Other Findings

  • When including the whole night, 20.00-05.59, in the night eating period, 60% of reference women compared to 83% of the obese women had a meal after 20.00 (p<0.001).
  • When breakfast was defined as a meal between 06.00 and 09.59, excluding drink meals, there was no difference in the consumption of breakfast (86% of reference women vs. 92% of obese women, p=0.26)
  • In a regression model, snack meals was a predictor of energy intake for both groups (for obese group, B=180.9, p=0.04, for refrerence group, B=167.3, p=0.04).
Author Conclusion:
The number of reported intake occasions across a usual day was higher in obese women compared with controls and the timing was shifted to later in the day.
Funding Source:
Government: SMRC
Reviewer Comments:

This study offers interesting, but probably not surprising, results; although the authors state that their finding of a higher meal frequency in the obese group differs from earlier studies.  In summary, they found that obese women:

  • consumed more energy (and other nutrients)
  • ate more later in the day
  • ate more often at non-traditional times.

The authors appeared to feel strongly that their method of collecting dietary information is superior but offer only marginal (r=0.7) test/re-test data to support its superiority.

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? Yes
  2.4. Were the subjects/patients a representative sample of the relevant population? Yes
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? 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%.) N/A
  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.) 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? 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? N/A
  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? No
  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? 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