PWM: Foods and Nutrients (2006)
- To ascertain the association between diet composition and body fat percent in 9-10-year-old children.
- To examine the influence of gender, total energy intake, fitness, physical activity, and parental BMI on the relationship between diet composition and adiposity.
Children qualified by being at least 9 and less than 11 years old.
not specified.
Study sample was recruited using newspaper advertisements and school flyers. Aproximately 1 week before the day of testing, the parents of each subject were sent a FFQ to be completed by a parent & child. The child physical activity questionnaire and physical data were completed in the research center. Height, weight, and skinfolds were measured after the questionnaire was completed. The 1-mile run/walk test was performed after the anthropometric measurements were obtained.
Dependent:
- 3 body fat groups were formed with as equal a number of subjects in each group as possible
- Estimated percent body fat % (Formula using skinfold measurements).
Independent:
- Food Frequency Questionnaire completed collaboratively by parents & children);
- Physical activity (questionnaire)
Control Variables:
- Gender,
- Total energy intake,
- Physical fitness (run/walk test),
- Parental body mass (self-reported height and weight).
Statistical Analysis: Regression analysis (to determine extent to which diet composition was associated with adiposity) & Partial correlations (calculated using multiple regression analysis to assess the relationship between macronutrient intake & body fat % after differences in potential confounders, such as total energy intake, aerobic fitness level & parental body mass were controlled for statistically.
Original Sample: 262 children (162 boys, 100 girls)
Withdrawals/Drop-Outs: subjects with missing data.
Final Sample: 253 children.
Location: Utah
Race/Ethnicity: not specified.
SES: not specified.
Age: 9 and 10 year olds.
Body fat % in children was positively and significantly related to body weight (r=0.81,P<0.0001) & BMI (r=0.83, P=0.0001).
Total Energy: Energy intake was negatively and significantly associated related to body fat %. Energy intake was inversely and significantly related to body fat after controlling for gender, body weight, and for gender, weight, fitness and parental BMI combined.
Dietary fat: Fat intake, calculated as a percentage of total energy, was positively related to adiposity (body fat %), before and after control for potential confounding variables.
Carbohydrates: % of energy derived from carbohydrate was inversely related to adiposity, before and after controlling for potential confounders.
Protein & Fiber:
- The relationship between % of energy derived from protein and body fat % was mixed depending on the variables controlled, as was the relationship between fiber intake & body fat.
- Both absolute protein (g) and % energy from protein were positively associated with body fat percentage only when gender & energy were controlled for – not when gender, energy, fitness or parental BMIs or when no variables were controlled for.
- Fiber was inversely associated with body fat % only when no variables were controlled for.
Results among 3 body fat groups: The fattest group consumed a significantly higher % of energy from fat, whereas the leanest children consumed the lowest – there was no significant difference among the groups regarding % energy from protein. There were also no significant differences in total energy consumed or in fiber intake among the groups.
University/Hospital: | Brigham Young University |
Strengths: Controlled for a number of potentially confounding variables.
Limitations: Cross-sectional Design.
Abstract incorrectly reported results of total energy data – suggesting total energy was positively associated with adiposity. The tabled results and write-up suggest the association is significant in the opposite (inverse) direction.
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) | 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? | 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? | 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? | ??? | |
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? | 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%.) | No | |
4.3. | Were all enrolled subjects/patients (in the original sample) accounted for? | No | |
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? | No | |
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? | 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? | 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? | 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)? | ??? | |
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? | ??? | |
10.2. | Was the study free from apparent conflict of interest? | Yes | |