PWM: Foods and Nutrients (2006)
Tucker LA, Seljaas GT, Hager R. Body fat percentage of children varies according to their diet composition. J Am Diet Assoc 1997; 97: 981-6.PubMed ID: 9284875
- 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.
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.
- 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).
- Food Frequency Questionnaire completed collaboratively by parents & children);
- Physical activity (questionnaire)
- 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.
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
|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|
|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|