Pediatric Weight Management

PWM: Family Influences (2006)

Citation:

Fisher JO, Birch LL. Restricting access to palatable foods affects children’s behavioral response, food selection and intake. Am J Clin Nutr 1999; 69: 1,264-1,272.

PubMed ID: 10357749
 
Study Design:
Within-subjects, quasi-experimental design
Class:
D - Click here for explanation of classification scheme.
Quality Rating:
Positive POSITIVE: See Quality Criteria Checklist below.
Research Purpose:
To test hypothesis that restricting access to a palatable food enhances children’s subsequent behavioral responses to, selection of, and intake of that restrained food.
Inclusion Criteria:
  • Experiment 1: Three to five year-old children attending daycare programs at The Pennsylvania State University Child Development Laboratory and their parents
  • Experiment 2: Three to six year-old children attending daycare programs at The Pennsylvania State University Child Development Laboratory and their parents.
Exclusion Criteria:
Child-parent dyads with missing data.
Description of Study Protocol:

Two experiments were conducted to test the hypothesis.

  • Experiment 1: Children's eating behavior was examined before, during and after five weeks of restricted access to a snack food. Children's food selection and intake were measured three weeks before and three weeks after the period of restriction. Children's behavioral response was measured both before and during five weeks of restricted access to a snack food.
  • Experiment 2: Children's selection of, intake of and behavioral response to a palatable snack snack food was examined. Children participated in four unrestricted snack sessions in which the restricted food was freely available through-out the snack session, followed by four restricted snack sessions in which access to the restricted food was limited. An additional food of acceptable but relatively lower preference was provided ad libitum throughout the experiment.

Statistical Analysis

  • Experiment 1: Descriptive statistics with means ± SD or SEMs, skewness and kurtosis were used. A two-way repeated measures analysis of variance was used for evaluation of food intake before and after the restriction as well as behavior before and during restriction.
  • Experiment 2: Means, SEMs and ranges were used. ANOVA was used to evaluate children's five minute selection, five minute intake and five minute behavioral response to the restriced food. Pearson’s product-moment correlation were used between parents’ reports of restricting access to the experimental food at home and the background variables.
Data Collection Summary:
  • Dependent variables: Child weight for height (measure weight and height)
  • Independent variables:
    • Food selection type and intake
    • Parents’ restrained eating and disinhibited eating (Stunkard and Messick’s Eating Inventory Questionnaire)
    • Parental restriction of access to the experimental foods at home (Questionaire)
  • Control variables: Gender.
Description of Actual Data Sample:
  • N: 
    • Experiment 1: 38 children
    • Experiment 2: 40 children (19 boys and 21 girls)
    • 32 mothers and 27 fathers
  • Attrition:
    • Experiment 1:31 (21 boys and 10 girls). One child refused to participate, one child was too young and five children were absent for most of the assessments and trials.
    • Experiment 2: 37. One child failed to comply with experimental procedures, two children were absent from more than one-third of all trials.
  • Age: Four to six years old
  • Ethnicity: Experiment 2: (80% White, 15% Asian, 4% Black, 1% Other) 
  • SES: Well-educated parents
  • Location: Pennsylvania.
Summary of Results:

Experiment 1

  • Restricting children's access to the target food resulted in an increased behavioral response to that food relative to the control food 
  • The increased response to the control food was greater for boys than girls during the restriction (P<0.05)
  • There was no significant effect of restriciton on children's intake or selection at three weeks before or three weeks after the trials
  • No significant effect of food type on children's intake was observed
  • A  main effect of time was observed in that children's consumption of both the target food (49.4±6.0g compared with 45.0±6.4g) and control food (51.5±5.8g compared with 38.5±4.7g) deceased over time (P<0.05) 
  • No significant differences between pre- and post-restriction were observed in the percentage of children selecting the target food as a snack (58% compared with 59%).

Experiment 2

  • Children's behavioral response to a palatable snack food was greater during restricted sessions than during unrestricted sessions. This effect did not differ by child's sex (P=0.16) or age (P=0.66).
  • An interaction was noted between the types of restricted food assigned and the session type (P<0.001); increases in children's behavioral responses for pretzel fish-shaped crackers than for cheese fish-shaped crackers
  • A main effect of restriction on children's selection of the restricted food showed a high selection during restricted snack periods than during unrestricted periods. This effect did not differ by type of experimental food used (P=0.39) or by child's age (P=0.65) or sex (P=0.16).
  • A main effect of session type on children's intake of the restricted food occurred; intake was higher during restricted snack sessions than unrestricted sessions
  • Children's behavioral response to the restricted food (37%±3% of total behavioral response to target and control foods during unrestricted sessions compared with 49%±3% in restricted sessions, P<0.01) and intake of restricted food (18%±2% of total target and control food intake during unrestricted session compared to 37%±4% in restricted sessions, P<0.001) increased during restricted sessions when expressed as a percentage of total activity.

Parent reports of restriction of foods was:

  • Positively related to level of education
  • Negatively related to parent BMI.

So, higher education level and lower BMI were associated with greater restriction of access to the experimental (highly palatable) food at home. 

Mother’s disinhibition was negatively related to parents’ reports of restricted access to the experimental food at home; r=-0.41 (P<0.05). That is, the greater the mother's disinhibition the greater the restriction to the experimental food.

Children’s weight status was positively related to parental restriction, with higher levels of reported restriction associated with higher child’s relative weight (weight for height);  r=0.43 (P<0.05).

Author Conclusion:
  • The results of this research suggest that restricting children’s access to palatable foods within their eating environment is not an effective means of promoting moderate intake of those foods and may in fact promote the intake of such foods
  • Gives credence to Constanzo and Woody’s theory that highly controlling approaches to child feeding undermine children’s ability to develop and exercise self-control over eating.
Funding Source:
Government: NIH grant no. ROI HD32973
Reviewer Comments:
  • Small sample size
  • The strength of the experimental manipulation in experiment 1 may not have been sufficient to produce an effect of restricted access on children's selection and intake outside the restricted context. The similarity of the target and control foods may have decreased the effect of the contrasting availability of the two foods. These foods may have been difficult to differentiate outside the experimentally restricted context.
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
  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
  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
  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
  4. Is the intervention or procedure feasible? (NA for some epidemiological studies) Yes
 
Validity Questions
  1. Was the research question clearly stated? 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
  1.1. 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
  1.2. Was (were) the outcome(s) [dependent variable(s)] clearly indicated? Yes
  1.3. Were the target population and setting specified? Yes
  1.3. Were the target population and setting specified? Yes
  2. Was the selection of study subjects/patients free from bias? 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
  2.1. 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
  2.2. Were criteria applied equally to all study groups? Yes
  2.3. Were health, demographics, and other characteristics of subjects described? Yes
  2.3. Were health, demographics, and other characteristics of subjects described? Yes
  2.4. Were the subjects/patients a representative sample of the relevant population? Yes
  2.4. Were the subjects/patients a representative sample of the relevant population? Yes
  3. Were study groups comparable? 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) N/A
  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? Yes
  3.2. Were distribution of disease status, prognostic factors, and other factors (e.g., demographics) similar across study groups at baseline? Yes
  3.3. Were concurrent controls or comparisons used? (Concurrent preferred over historical control or comparison groups.) No
  3.3. Were concurrent controls or comparisons used? (Concurrent preferred over historical control or comparison groups.) No
  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? 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? N/A
  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
  3.5. 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
  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? Yes
4. Was method of handling withdrawals described? Yes
  4.1. Were follow-up methods described and the same for all groups? Yes
  4.1. Were follow-up methods described and the same for all groups? Yes
  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%.) Yes
  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%.) Yes
  4.3. Were all enrolled subjects/patients (in the original sample) accounted for? Yes
  4.3. Were all enrolled subjects/patients (in the original sample) accounted for? Yes
  4.4. Were reasons for withdrawals similar across groups? Yes
  4.4. Were reasons for withdrawals similar across groups? Yes
  4.5. If diagnostic test, was decision to perform reference test not dependent on results of test under study? N/A
  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. 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
  5.1. 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
  5.2. 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? N/A
  5.3. In cohort study or cross-sectional study, were measurements of outcomes and risk factors blinded? N/A
  5.4. In case control study, was case definition explicit and case ascertainment not influenced by exposure status? N/A
  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
  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. 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? Yes
  6.1. In RCT or other intervention trial, were protocols described for all regimens studied? Yes
  6.2. In observational study, were interventions, study settings, and clinicians/provider described? 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? 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
  6.4. 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
  6.5. Were co-interventions (e.g., ancillary treatments, other therapies) described? N/A
  6.6. Were extra or unplanned treatments 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
  6.7. 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
  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. 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
  7.1. 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
  7.2. 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
  7.3. 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
  7.4. 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
  7.5. Was the measurement of effect at an appropriate level of precision? Yes
  7.6. Were other factors accounted for (measured) that could affect outcomes? ???
  7.6. Were other factors accounted for (measured) that could affect outcomes? ???
  7.7. Were the measurements conducted consistently across groups? 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. 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
  8.1. 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
  8.2. 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
  8.3. 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
  8.4. 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)? N/A
  8.5. Were adequate adjustments made for effects of confounding factors that might have affected the outcomes (e.g., multivariate analyses)? N/A
  8.6. Was clinical significance as well as statistical significance reported? 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
  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. Are conclusions supported by results with biases and limitations taken into consideration? Yes
  9.1. Is there a discussion of findings? Yes
  9.1. Is there a discussion of findings? Yes
  9.2. Are biases and study limitations identified and discussed? 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. Is bias due to study's funding or sponsorship unlikely? Yes
  10.1. Were sources of funding and investigators' affiliations described? Yes
  10.1. Were sources of funding and investigators' affiliations described? Yes
  10.2. Was the study free from apparent conflict of interest? Yes
  10.2. Was the study free from apparent conflict of interest? Yes