Pediatric Weight Management

PWM: Eating Behaviors of Children (2006)

Citation:
Crawley H, Summerbell C. Feeding frequency and BMI among teenagers aged 16-17 years. Int J Obes, 1997;21:159-161. PubMed ID: 9043972
 
Study Design:
Cross-Sectional Study
Class:
D - Click here for explanation of classification scheme.
Quality Rating:
Neutral NEUTRAL: See Quality Criteria Checklist below.
Research Purpose:

To investigate if and how the relationship between feeding frequency and BMI in free-living teenagers aged 16-17 years old is dependent on the validity of recorded dietary intakes, BMI, self-reported dieting and body image.

Inclusion Criteria:
Not specified.
Exclusion Criteria:
Not specified.
Description of Study Protocol:

Recruitment

  • Described elsewhere (Crawley HF. Br J Nutr, 1993;70:15-26); subjects from the 1970 longitudinal birth cohort study.

Design

  • Students completed diet diary and had anthropometric measurements taken.

Statistical Analysis

  • Not described.

[Note: Titled as a "Short Communication"]

Data Collection Summary:

[Note: No blinding?]

Independent variables

  • Feeding frequency (each eating occasion where calories consumed separated by at least 30 minutes, as assessed by a four-day diet diary).

Dependent Variables

  • BMI (measured weight and height).

Other Variables

  • Self-assessed body weight (feel under, normal or overweight).

Control Variables

  • Gender (separate analysis)
  • Under-reporting (non-dieting subjects who reported energy intake below 1.35 estimated BMR; removed from analysis)
  • True dieting (same as above + reported dieting behavior; removed from analysis).
Description of Actual Data Sample:
  • N: 731 (298 males, 433 females)
  • Age: 16-17 years
  • Ethnicity: Not specified
  • Other demographics: Not specified
  • Location: England.
Summary of Results:

Feeding Frequency with Total Sample

  • Inversely related to BMI for both males (P<0.005) and females (P<0.05)
  • Feeding frequency was 6.5, 6.2 and 5.6 among males with BMI <20, 20-25 and >26, respectively
  • Analogous numbers for females were 6.5, 6.3 and 6.4.

Feeding Frequency with Under-reporters (N=?) Removed

  • Inverse relationship remained for both males (P<0.025) and females (P<0.05)

Feeding Frequency with True Dieters (N=26 males, 121 females) Removed

  • Inverse relationship disappeared for males, but remained for females
  • Overweight male dieters (N=11) had lower feeding frequency than other males
  • Inverse relationship for females disappeared when normal or underweight females, who were not dieting but who considered themselves to be overweight (N=7), were removed from analysis.
Author Conclusion:

The relationship observed in free-living populations, that feeding frequency is directly related to BMI, appears to be an artifact of reported eating behavior in overweight dieting males and among a group of normal weight, non-dieting females who feel overweight. Under-reporting of dietary intake alone, therefore, does not explain the apparent feeding frequency/BMI relationship among teenagers.

Funding Source:
University/Hospital: University North London, The Royal Free Hospital School of Medicine (London)
Reviewer Comments:

Strengths

  • Described how determined an eating occasion.

Weaknesses

  • No multivariate analysis
  • Study recruitment and protocols and subject demographics not well described (described in other publication?)
  • Convenience sample
  • BMI measure not blinded

Other

  • Pulled the referenced Crawley paper to get more study details for quality grading, but did not answer most of questions (e.g., inclusion/exclusion criteria, sample selection).
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? No
  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? N/A
  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? No
  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? No
  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%.) ???
  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? 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? No
  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? 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? N/A
  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? No
  8.1. Were statistical analyses adequately described and the results reported appropriately? No
  8.2. Were correct statistical tests used and assumptions of test not violated? ???
  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)? No
  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? 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? ???
  10.2. Was the study free from apparent conflict of interest? Yes