AWM: Eating Frequency and Patterns (2013)

Study Design:
- Click here for explanation of classification scheme.
Quality Rating:
Research Purpose:
To examine whether age, energy intake, baseline BMI, level of physical activity, smoking status, alcohol intake, and level of morbidity modify the relation of eating occasions with weight change; the association of weight change with frequency of eating occasions was also examined within different strata of these variables.
Inclusion Criteria:
Previously reported.
Exclusion Criteria:
Previously reported.
Description of Study Protocol:

Recruitment Previously reported

Design Data was used form the NHANES I (1971-75) and NHANES I Epidemiologic Follow-up Study (1982-84) (NHEFS).

Blinding used (if applicable) NA

Intervention (if applicable) NA

Statistical Analysis regression analyses

Data Collection Summary:

Timing of Measurements 2 times, in 1971-75 and 1982-84

Dependent Variables

  • weight change

Independent Variables

  • frequency of eating occasion (entered as a continuous and categorical variable)- frequency of eating occasions was estimated by summing the energy yielding consumption reported at one time using a single 24-hour recall at Time 1.  Occasions when non-caloric intake was reported was not counted.  At follow-up respondents were asked one question each regarding the number of meals and number of snacks consumed daily and weight was measured.

Control Variables

  • race
  • education (<12, 12, >12 years)
  • smoking status (never, former, current)
  • age
  • baseline BMI
  • length of follow-up
  • energy intake - 1 24-hour recall
  • alcohol (0, <9.35 g, > 9.35 g)
  • special diet status (yes or no)
  • parity
  • self-reported physical activity at baseline and follow-up (a lot, moderate, and little)
  • presence of physician confirmed morbidty (0=no, 1=1 positive response, 2=2 positive responsed, and 3 >3 positive responses)
Description of Actual Data Sample:

Initial N:For NHANES I: 14,407, for NHEFS 10,424

Attrition (final N): 7141 (large numbers were excluded for missing or unreliable data).  Resulting n is 68% of eligible cohort of 10,424.  2580 men, 4567 women

Age: men=44.5 years, women = 45.9 years

Ethnicity: not reported

Other relevant demographics: Not reported for entire sample.  Although 68% of the original smple was used for analysis, this sub-sample was similar to the original cohort in terms of age, eating frequency, baseline BMI, and energy intake.

Anthropometrics not reported for entire sample

Location: U.S.

Summary of Results:

Summary of Results (all Ps<0.05 unless otherwise reported):

  • Mean weight change ranged between 1.88 to 2.66 kg (3.96 to 5.85 lbs) for men and 2.06 to 2.98 kg (4.56 to 6.56 lb) in women.
  • In women, mean baseline BMI, triceps skinfold, suscapular skinfold, and plasma cholesterol, decreased with increasing baseline frequency of eating occasions (P<0.006).
  • In men, mean baseline BMI and subscapular skinfold decreased with increasing baseline eating frequency; trends in triceps skinfold and plasma cholesterol were not consistent.
  • Mean dietary energy and alcohol intake increased with increasing baseline eating frequency in both men and women.
  • At follow-up, the highest eating frequency category (>6/d) was associated with largest mean weight change and baseline BMI in women, but not men.
  • Mean plasma cholesterol at baseline was inversely associated with frequency of eating at follow-up in women but not men.
  • Mean plasma cholesterol measured at baseline was inversely associated with frequency of eating at follow-up in women but not men.
  • For every unit increase in frequency of eating at baseline, men and women gained 0.22  kg (.48 lbs) (P=0.03) and 0.34 kg (.75 lbs) (P=0.0002) of body weight, respectively, over the period of follow-up.  After adjustment for age, and other confounders, this relationship was no longer significant.
  • Re-analyzing data excluding persons reporting being on a special diet did not change the pattern of results.
Author Conclusion:

There was no independent association of frequency of food ingestion estimated from a 24-h dietary recall with prospective weight change or frequency of eating estimated from answers to questions on number of meals and snacks consumed daily with weight change over the preceding 8-10 years in the NHEFS cohort.

Funding Source:
Government: National Cancer Institute
University/Hospital: Queens College of City University of New York
Reviewer Comments:
This study offers little insight into the effect of eating frequency and weight change.  Although a large number of variables were gathered, the dietary intake included only 1 24-hour recall.  It is likely that this 24-hour recall was not representative of intake.  Additionally, there was no attempt to exclude implausible intakes.  Last, the definition of eating occasion was very general and the failure to define amount eaten or time between previous and subsequent intake may have resulted in the eating frequency variable having a great deal of 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? 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? ???
  2.2. Were criteria applied equally to all study groups? N/A
  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? 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%.) No
  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? 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? 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? 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? 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? 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? 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? No
  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? No
  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? No
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