Pediatric Weight Management

PWM: Foods and Nutrients (2006)

Citation:

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
 
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 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.
Inclusion Criteria:

Children qualified by being at least 9 and less than 11 years old.

Exclusion Criteria:

not specified.

Description of Study Protocol:

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.

Data Collection Summary:

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.

Description of Actual Data Sample:

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.

Summary of Results:

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.

Author Conclusion:
These findings indicate that the macronutrient intake of children, particularly dietary fat and carbohydrate, may play a role in adiposity, independent of the influence of total energy intake, gender, physical fitness and parental BMI.
Funding Source:
University/Hospital: Brigham Young University
Reviewer Comments:

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
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