PWM: Eating Behaviors of Children (2006)
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.
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"]
[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).
- N: 731 (298 males, 433 females)
- Age: 16-17 years
- Ethnicity: Not specified
- Other demographics: Not specified
- Location: England.
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.
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.
University/Hospital: | University North London, The Royal Free Hospital School of Medicine (London) |
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
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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 | |