AWM: Eating Frequency and Patterns (2013)

Study Design:
- Click here for explanation of classification scheme.
Quality Rating:
Research Purpose:
To investigate snacking frequency in relation to energy intake and food choices, taking physical activity into account, in obese vs. reference men and women.
Inclusion Criteria:

Aged 30-60, BMI > 30

Exclusion Criteria:
None stated.
Description of Study Protocol:

Recruitment The obese participants volunteered to participate in a study about diabetes in obese subjects.  Subjects were participants in the baseline examination preceding the intervention.  The reference group were recruited from the Swedish Obese Subjects reference study.

Design All participants underwent a health examination including anthropometrics (weight and height), blood samples and completed questionnaires on meal patterns, dietary intake, and SES. Dietary questionnaires included a self-administered meal pattern measure describing habitual daily intake and a self-administered measure describing daily energy, macro- and micronutrient intake during the last 3 months.  Total energy intake was divided into 15 different food groups for other analyses.

Blinding used (if applicable) NA

Intervention (if applicable) NA

Statistical Analysis Logistic regression, likelihood ratio test, and general linear modeling.  When analyzing snack categories, a Bonferroni correction for multiple tests was used.

Data Collection Summary:

Timing of Measurements  1 time

Dependent Variables

  • Total energy intake - measured wit a self-administered measure describing daily energy during the last 3 months. 
  • Metabolic measures - blood samples (analyzed for cholesterol, triglycerides, BG and insulin)

Independent Variables

  • Number of intake occasions/intake frequency  - on the self-administered meal pattern measure describing habitual daily intake, defined as total number of main meals, light meals/breakfasts, snacks and drink-only. 
  • Snacking frequency - in sub-analyses, snacking occasions were divided into 4 categories: 0, 1, 2, and >3 per day.

Control Variables In some analyses, energy, age, and/or physical activity were used as control variables.

Description of Actual Data Sample:


Initial N: 1891 obese men, 2368 obese women, 505 reference men, 587 reference women.

Attrition (final N): Data was apparently taken from exisiting data - no attrition was reported.

Age: obese men = 45.8 +/- 7; obese women = 43.3 +/- 8.2; reference men = 49.7 +/- 7.0; reference women = 49.3 +/- 7.0 years.

Ethnicity: not stated

Other relevant demographics:  A larger proportion of the obese men reported low educational attainment vs. the reference men.

Anthropometrics obese men = 37.1 +/- 4.3; obese women = 38.1 +/- 4.5; reference men = 25.8 +/- 3.4; reference women = 24.7 +/- 4.1

Location: Sweden

Summary of Results:

Intake occasions, energy intake and physical activity in men vs women in obese and reference groups
  obese men obese women reference men reference women P P
  n=1891 n-2368 n=505 n=587 obese vs. reference women vs. men
Intake occasions 5.8+/-1.9 5.9+/-1.6 5.2+/-1.6 5.3+/-1.3 <0.001 0.055
Eating occasions 4.2+/-1.3 4.8+/11.3 3.8+/-1.1 4.1+/-1.1 <0.001 <0.001
Main meals 1.4+/-0.5 1.4+/-0.5 1.2+/-0.5 1.3+/-0.4 <0.001 0.461
Light meals/breakfast 1.2+/-0.8 1.3+/-0.7 1.2+/-0.8 1.3+/-0.7 0.614 <0.001
Snacks 1.6+/-1.2 2.0+/-1.2 1.3+/-1.0 1.6+/-1.0 <0.001 <0.001
Drink-only 1.6+/-1.6 1.2+/-1.3 1.4+/-1.4 1.2+/-1.2 0.007 <0.001
Energy (kcal) 3234+/-1142 2683+/-1025 2766+/-867 2223+/-716 <0.001 <0.001
Sedentary occupation (%) 28.9 25.0 29.7 26.4 0.724 0.008
Sedentary leisure time (%) 31.5 32.3 9.5 11.0 <0.001 0.463

Number of intake occasions and energy intake

  • Number of intake occasions was higher in women than in men (P<0.055).
  • Obese men and women most frequently reported 6 intake occasions compared to 5 in the reference men and women (P<0.01)
  • Obese men and women more frequently reported snacks (P<0.01).
  • The obese group reported a higher energy intake (P<0.001).
  • Number of intake occasions was independently related to obesity (OR=1.21, CI=1.15-1.27, P<0.001) and for energy (kcal/1000) (OR=1.49, CI=1.37-1.62, P<0.001). Using number of snacks instead of intake occasions in the model, OR for snacks was 1.27 (CI=1.19-1.35, P<0.001) and for energy (kcal/1000) OR was 1.48 (CI=1.37-1.61, P<0.001).

Intake frequency in relation to energy intake

  • Women snacked more than men (P<0.001)
  • Energy intake increased significantly by increasing number of principal meals in the obese but not the reference group.
  • There was a negative trend in energy intake by drink-only category in all groups except the reference women.

Snacking frequency in relation to dietary intake

  • Increases in energy intake per day between the lowest (0) and highest (> 3) snack categories were 830 kcal for the obese men, 640 kcal for the reference men, 584 kcals for the obese women, and 312 kcal for the reference women.
  • In obese men and women, the proportion of protein intake decreased (P<0.05) by increasing snack category.
  • BMI was not related to number of snacks per day after correction for multiple comparisons.

Snacking frequency and energy intake from the 15 food groups

  • A difference in trend between obese and reference groups was found for the relation between energy intake and snacking frequency for 3 food groups: cakes/cookies (P<0.01, with a steeper increase in obese groups), candies/chocolate (P<0.05, trend was not significant in reference women), and desserts (P<0.01, only significant in the obese group).
  • A difference was found in trend between obese and reference groups (P<0.05) for energy intake in a combined food group (main + light meals) by increasing snacking frequency.

Snacking frequency in relation to metabolic variables

  • The metabolic variables blood pressure, b-glucose, s-insulin, s-cholesterol, s-tricglycerides, and s-HDL were not related to snacking frquency in any of the groups.
Author Conclusion:
This study showed that men and women with obesity have more frequent intake occasions, higher energy intake and more sedentary lesiure time than a reference population.  Furthermore, we found that obese subjects were more frequent snackers than reference subjects.  High physical activity did not explain high energy intake and snacking.  Certain food groups were associated with snacking and contributed considerably to energy intake.  Food choices and snacking need to be considered in obesity treatment, prevention and general dietary recommendations.
Funding Source:
Government: Swedish Research Council
F. Hoffman-La Roche
Pharmaceutical/Dietary Supplement Company:
Reviewer Comments:
Although this is a well-done study with appropriate statistical analyses, their findings do not support a relationship between intake frequency or snacking and BMI.  This is unusual, given that both intake frequency and snacking were related to greater overall intake.  One reason for this may be the use of dietary pattern and usual intake questionnaires rather than gathering intake in a more traditional manner (recalls or records).  It is likely that at least some intake was underreported and use of the measures did not allow the researchers to screen out improbable intakes. Additionally, the obese group had volunteered for an obesity study and may have been modifying their intake when they completed the questionnaires.  However, the findings that intake increased more in the obese group when they compared 0 snacks/day to > 3 snacks/day and that protein intake decreased as number of snacks increased in the obese group do provide insights into the effect of snacking and might suggest that protein intake has a positive effect in increasing satiety and decreasing subsequent hunger and intake.
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? 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? Yes
  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.) Yes
  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? 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? 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