AWM: Eating Frequency and Patterns (2013)


Kent LM, Worsley A. Breakfast size is related to body mass index for men, but not women. Nutr Res. 2010; 30(4): 240-245.

PubMed ID: 20534326
Study Design:
Trend Study
D - Click here for explanation of classification scheme.
Quality Rating:
Neutral NEUTRAL: See Quality Criteria Checklist below.
Research Purpose:
  • To analyze data from cross-sectional, screening surveys to compare the association of breakfast size on BMI
  • To examine the effect of relative breakfast size on BMI in males and females
  • To examine possible confounders of this relationship.
Inclusion Criteria:

Residents of the general community around the Sydney Adventist Hospital from 1976 until 2000. After 2000, large corporations were invited to send their corporate executives for a comprehensive evaluation of the health and associated risk factors.

Exclusion Criteria:

None noted.

Description of Study Protocol:


Between 1976 and 2000, residents of the general community around the Sydney Adventist hospital were invited to take part in heart health screening surveys that assessed heart health, food consumption and other lifestyle practices. After 2000, these services were no longer offered, rather large corporations were invited to send their corporate executives for a comprehensive evaluation of their health and associated risk factors.


Trend study.

Blinding Used

Respondents were randomly selected from these annual surveys in 1976, 1986 and 2005. 


At the time of the screening, hospital staff asked respondents to complete a questionnaire that included a food frequency questionnaire, frequency of various moderated and vigorous physical activities, dietary habits, smoking and alcohol usage and lifestyle.

Statistical Analysis

  • Independent T-tests were performed to assess differences in ages between men and women for each year selected (presented as means ± SEM)
  • Univariate analysis of variance was conducted on each sex for:
    • Demographic variables: 
      • Age
      • Sex
      • Religion
      • Marital status
      • Education
    • Food variables:
      • Eating behaviors:
        • Eating between meals
        • Breakfast
        • Regular meals patterns
        • Dieting
      • Lifestyle variables:
        • Smoking
        • Physical activity
        • Sleep
        • Time urgency (where supplied)
  • Each of the demographic, food and lifestyle variables found to be significantly associated with body mass index was tested by backward linear regression
  • Spearman rho was used to calculate correlation coefficients between breakfast size and various foods, using two-tailed tests of significance
  • Forward linear regression was used to test possible breakfast confounders of physical activity and vegetarianism
  • All differences were considered significant if P<0.05. 
Data Collection Summary:

Timing of Measurements

All data was collected at the time of the screening.

Dependent Variables

Biomedical indices:

  • Height
  • Weight
  • Body mass index.

Independent Variables

  • Food Frequency Questionnaire: In 1976, 42 different foods and drinks were included in the questionnaire, as well as dietary practices (relative breakfast size, dieting to lose weight, frequency of cut fat from meat and eating between meals). In 1986, these foods and dietary practices were replicated with the addition of fish and cream. In 2005, the questionnaire differed slightly in that the number of meats, milks and dessert foods was reduced, and there was more information about takeaways, low-energy and low-fat foods and the relative size of dinner. 
  • Breakfast Question: In 1976 and 1986, participants were asked to compare the amount they ate for breakfast with a standard breakfast that comprised a bowl of cereal, a serving of fruit or juice, a cup of milk, and a slice of toast with juice. In 2005, participants were asked whether their breakfast was a large meal, moderate, a small meal or a cup of coffee, piece of toast or less.

Control Variables

Possible Confounders: Vegetarianism, physical activity, and lifestyle factors. Vegetarianism was determined from the aggregate score when meat was consumed "never" or "less than once per week." Physical activity (in 1976 and 1986) was assessed by questions about frequency of participation in walking, running, cycling, swimming, tennis, vigorous gardening and other vigorous activity. In 2005, participants recorded number of days exercised, time (minutes) of each exercise session and intensity (low, moderate or high). Other lifestyle factors examined included hours of sleep per night, smoking status (current, past and never smoked), frequency of alcohol consumption and number of drinks consumed per sitting.

Description of Actual Data Sample:
  • Initial N:
    • 1976: 384 men and 338 women
    • 1986: 244 men and 229 women
    • 2005: 270 men and 62 women
  • Attrition (final N):
    • 1976: 384 men and 338 women
    • 1986: 244 men and 229 women
    • 2005: 270 men and 62 women
  • Age: Mean age of men and women:
    • 1976: Men=44.5±0.6; women=45.9±0.7
    • 1986: Men=44.9±0.9; women=43.7±1.1
    • 2005: Men=49.7±0.6; women=47.6±1.3
  • Other relevant demographics:
    • Over-sampling in 1976 and 1986 accommodated the large number of vegetarians present in these years (29.3% in 1976 and 19.4% in 1986)
    • The proportions of men and women in the samples were similar to the general population in 1976 and 1986, but contained more men in 2005
    • The sample was older, was better educated and had more married individuals in both 1976 and 1986 and was older in 2005 than the general population
  • Anthropometrics: BMI was determined but not reported as a mean for each sampling group
  • Location: Sydney, Australia.
Summary of Results:

Key Findings

  • Age comparison of men and women: No differences in the mean ages of male and female participants in any of the years examined; however, men and women in 2005 were older than in previous years
  • Relationship of breakfast consumption to BMI:
    • Reported breakfast amount increased while BMI decreased in men (this trend was observed in all three years). However, this relationship was not observed among women.
    • Male vegetarian participants had lower BMI than did non-vegetarians in 1976, 1986 and 2005
    • The relationship between breakfast and BMI was much stronger among male vegetarians than male non-vegetarians
    • Cereals and fruit were strongly associated with breakfast in all three years; spreads were more important in 1986 than the other years
    • Increasing coffee consumption (particularly in 1986 and 2005) was associated with the trend toward smaller breakfasts or breakfast skipping
    • Other food or eating-related variables found to be positively associated with men's BMI included the frequency of consumption of chicken, wieners (sausages) and alcohol together with dieting to lose weight
    • Food variety and the frequency of consumption of spreads were negatively related to BMI for men in 1976
    • In 1986, eating between meals and the frequency of consumption of coffee and table salt were associated with increases in BMI, whereas physical activity was negatively associated with BMI. 
Author Conclusion:
  • Results of this study confirm that smaller breakfasts were associated with higher BMI
  • Skipping breakfast or the consumption of small breakfasts together with the consumption of coffee, table salt, and energy-dense foods; eating between meals; and dieting to lose weight seemed to be associated with increased BMI among men but not women
  • Increasing coffee consumption was associated with the trend toward smaller breakfasts or breakfast skipping.
Funding Source:
Sanitarium Health Food Company
Food Company:
University/Hospital: Deakin University in Melbourne, Australia
Other: Australian Research Council grant
Reviewer Comments:

Different samples and different instruments used for the three cross-sectional surveys.

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? No
  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) Yes
  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.) Yes
  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%.) N/A
  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? 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? 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? No
  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? 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? No
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