AWM: Eating Frequency and Patterns (2013)

Study Design:
- Click here for explanation of classification scheme.
Quality Rating:
Research Purpose:

To test whether individual eating styles are associated with overweight and obesity in a population sample of young adult twins and a sub-sample of monozygotic twins.

Inclusion Criteria:
  • Paraticipants in the FinnTwin16 study
  • 16 years old at baseline.
Exclusion Criteria:

Individuals with self-reported:

  • Weight-affecting diseases
  • Anorexia and bulimia nervosa
  • Diabetes
  • Inflammatory bowel disease
  • Chronic diarrhea
  • Celiac disease
  • Hypo- or hyperthyroidism
  • Lupus
  • Mental retardation
  • Malignancies
  • Cerebral palsy
  • Other mobility disorders.
Description of Study Protocol:


Participants were recruited for the FinnTwin16 study. Recruitment methods were not outlined.


Prospective cohort study.

Statistical Analysis

  • Differences between eating styles and BMI and overweight/obesity categories were investigated using cross-tabulations, Pearson χ² test of independence and linear and logistic regression, all corrected for clustered sampling within twin pairs
  • The relationship of categorical BMI at T4 and eating styles at T4 was assessed using polytomous logistic regression models, controlling for BMI at T1 and correcting for clustered sampling
  • In twin analysis, Pearson and polychoric correlation coefficients were computed to assess intra-pair twin resemblance by zyosity group. Monozygotic twin pairs were compared using conditional logistic regression.
Data Collection Summary:

Timing of Measurements:

  • Participants were assessed at baseline or T1 (16 years), age 17 (T2), 18.5 years (T3) and 22 to 27 years (T4) of age
  • Data from responses at T1 and T4 were used in this study
    • T1 was between 1991 and 1995
    • Data was collected at T4 between 2000 and 2002.

Dependent Variables

BMI was calculated based on self-reported weight and height. Weight status was categorized based on BMI as follows:

  • Normal weight: BMI less than 25kg/m2
  • Mild overweight: BMI 25 to less than 27kg/m2
  • Moderate overweight: BMI 27 to less than 30kg/m2
  • Obesity: BMI 30kg/m2 or higher. 

Independent Variables

  • Eating styles as self-reported on questionnaire that assessed restrictive/overeating, snacking, health-conscious, emotional, and externally induced eating styles.
  • Participants were asked to choose the one of four options that best characterized their eating styles.

Control Variables

Zygosity: Twins zygosity was determined by the baseline questionnaire and, when necessary, supplemented with photographs, fingerprints and DNA-marker studies. Twin pairs were classified as monozygotic, dizygotic or unknown zygosity.



Description of Actual Data Sample:
  • Initial N: 4,667 individuals (2,545 women and 2,122 men) were enrolled at baseline (T1)
  • Attrition (final N): 4,393 individuals (2,333 women and 2,060 men) completed the study. 
    • 251 participants were excluded from the final data analysis because of exclusion factors identified at T4
    • 23 individuals were excluded due to missing data on BMI at T4
    • The sub-sample of monozygous twins included 358 female and 242 male twin pairs
  • Age: 16 years at baseline
  • Anthropometrics: BMI of the study population at baseline was not reported
  • Location: Finland.
Summary of Results:

Key Findings

  • Restrictive eating, overeating and alternating restricting/overeating at T4 were significantly more common in women than in men (P<0.0001) and significantly more common in obese than non-obese (P<0.0001)
  • At T4, there was a lower likelihood of attempting to maintain a healthy eating style in overweight [mild overweight: OR women=0.6 (0.4 to 0.9, P<0.01); OR men=0.8 (0.6 to 1.0); moderate overweight: OR women= 0.4 (0.2 to 0.7, P<0.001); OR men=0.5 (0.4 to 0.7, P<0.001)] and obese [OR women=0.2 (0.1 to 0.3, P<0.001); OR men=0.4 (0.2 to 0.7, P<0.0001)] individuals compared to their normal-weight peers
  • Restrictive eating, frequent snacking between meals, consuming food and snacks in the evening and avoiding fatty foods were associated with obesity in both men and women
  • Both obese women (OR=4.4, 95% CI: 1.3 to 14.1, P<0.05) and overweight (OR=3.2, 95% CI: 1.3 to 7.9) men were significantly more likely to be prompted to eat by visual cues than their normal-weight peers
  • When all eating styles were entered into a multi-variable model predicting obesity, controlling for gender and BMI at T1, restricting/overeating eating style at T4 was associated with obesity at T4 (OR=3.4, 95% CI: 2.2 to 5.3, P<0.001) and health-conscious eating style at T4  decreased the risk of obesity at T4 (OR=0.9, 95% CI: 0.8 to 1.0, P<0.01)
  • When controlled for genetic background, restricting/overeating eating style was still statistically significantly associated with excess weight.

The Association of Regular, Restrictive and Overeating Eating Styles with Obesity

  Regular Eating Restrictive Eating Frequent Overeating Alternating Restricting/Overeating
Mean BMI 21.1  23.25  23.94  23.86 
% Obese 0.94 5.38  9.12  8.87 
N 1,376  260  449  124 
Mean BMI 23.29  25.67  25.90  26.19 
% Obese 2.26  9.68  10.97  4.55 
N 1,590  62  383  22 

Obesity is defined at BMI 30 or more.

The Association of Obesity and Eating Styles at T4, Adjusted for BMI at T1; Odds Ratios from the Best-fitting Multi-variable Logistic Regression Model


     Both Genders 


  Odds Ratio (95% CI)  
Restrictive eating 3.4 (2.2 to 5.3) <0.001
Frequent overeating 1.7 (0.9 to 3.4)  
Alternating overeating and restricting 2.6 (1.1 to 6.4)  
Health-conscious eating 0.9 (0.8 to 1.0) <0.01
BMI at 16 years 1.8 (1.7 to 1.9) <0.001

Intra-pair Twin Correlations of BMI and Eating Styles by Twin Zygosity

Same-sex Twin Pairs Opposite-sex Twin Pairs
Women Men
N (pairs)** 358 297 242 288 614
BMI at T1 0.89 0.37 0.78 0.40 0.29
BMI at T4 0.79 0.42 0.79 0.26 0.24
Restrictive/overeating 0.47 0.17 0.43 * 0.15
Frequent snacking between meals 0.31 0.03 0.40 0.16 0.22
Frequent snacks replace meals 0.45 0.33 0.36 0.23 0.00
Highest food consumption in the evening 0.44 0.29 0.51 0.34 0.14
Grazing throughout the evening 0.45 0.17 0.40 0.16 0.22
Eating while watching TV 0.45 0.29 0.51 0.34 0.29
Health-conscious eating 0.52 0.58 0.65 0.19 0.15
Avoiding fatty foods 0.54 0.09 0.41 0.29 0.18
Avoiding calories 0.42 0.20 0.40 0.33 0.15
Visual cues prompt eating 0.49 0.37 * * *
Food used as a reward 0.40 0.15 0.24 0.29 0.14
Comfort eating 0.37 0.34 0.49 0.13 0.01

*Intra-pair correlation could not be computed because no twin pair was concordant for the presence of this trait.

**Only complete twin pairs of known zygosity who did not have chronic weight-affecting illnesses were included in the analysis (N=1,799 pairs).


Author Conclusion:
  • The authors conclude that eating styles of obese young adults differ markedly from their normal weight counterparts, with clear sex differences. Patterns of restrictive eating, overeating and alternating restrictive/overeating were most commonly associated with obesity.
  • According to the authors, this study also implies that a genetic pre-disposition alone does not dictate body weight, but that environmentally influenced behavioral behavior patterns, such as eating styles and healthful eating choices, also make a difference.
Funding Source:
Government: European Union Frfty Framework Program, Academy of Finalnd
University/Hospital: Helsinki University Central Hospital
Finnish Cultural Foundation
Reviewer Comments:
  • To identify healthy eating styles, an 11-item questionnaire was used. Five questions assessed snacking/grazing styles, three addressed health-conscious eating, two addressed emotional eating, and one addressed externally cued eating
  • The data was based only on self-reported information and is subject to reporting error
  • BMI was self-reported and subject to reporting error.
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? ???
  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? No
  2.4. Were the subjects/patients a representative sample of the relevant population? ???
3. Were study groups comparable? ???
  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? ???
  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? 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? 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.) No
  5.3. In cohort study or cross-sectional study, were measurements of outcomes and risk factors blinded? ???
  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? 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? Yes
  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? ???
  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? N/A
  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? No
  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