EAL

NGHC: Prevention of Chronic Disease (2013)

Citation:

Study Design:

Class:

- Click here for explanation of classification scheme.

Quality Rating:

Research Purpose:

To determine the effects of repeated exposure to a large portion of an entrée on preschool-aged children’s awareness of portion size, self-selected portion size, and food intake.
To evaluate associations of children’s responsiveness to portion size with weight status and overeating.

Inclusion Criteria:

not specified

Exclusion Criteria:

5 children excluded from analysis because mean intake of main entrée <10 g across 4 reference lunches; not significantly different from others by age, BMI-for-age Z score. Also some missing data and outliers (>2 SD).

Description of Study Protocol:

Recruitment

All preschool children (2 classrooms) attending full-day daycare programs at Penn State Univ. invited; only 1 family refused screening

Design

within subject cross-over: once a week for 4 weeks (4 times) = age-appropriate (ref) or large (double ref) portion of entrée (mac & cheese) as part of a standard lunch (milk, applesauce, carrots, sugar cookies) at research center, once a week for 2 weeks (2 times) self-selected same size-entrée as above; repeat of above crossing-over to other portion size (order balanced for age and sex)

Note: ref portion = 125 g for younger (<4y), 175 g for older children (>=4y) [sim to CSFII portion sizes]

Statistical Analysis

Each child served as own control; ANOCOVA to evaluate portion assignment order, sex and age as potential covariates of changes in the dependent variables; correlations to determine extent to which each dependent variables measuring the children’s response to repeated exposure to large portions was associated with weight and eating in the absence of hunger

Data Collection Summary:

(no blinding)

Independent variables

entrée portion size, self-served or provided

Dependent variables

Intake of intervention lunches (weighed) Sweetened soft drinks (carbonated and non-carbonated, excluding 100% fruit juice)
No. of bites of entrée taken (direct observation by recorded by behavioral coder) & bite frequency (sum of all bites of entrée during 15-min lunch period)
Average bite size (calculated as total grams entrée consumed divided by total number of bites of entrée)
Food preference and familiarity (subjective measure)

Other variables

Hunger (subjective measure)
Eating in the absence of hunger (10-min test with 10 snack foods after lunch)
BMI z score (measured weight, height)

Control variables

none in analyses with BMI z score (but as children compared to themselves as controls, not relevant)

Description of Actual Data Sample:

N: 35 children (17 boys, 18 girls); data reported on 30 children (for most analyses; did have some missing/incomplete data for some measures)

Age: mean 4 y (2.9 – 5.1 y)

Ethnicity: 1 African American, 4 Asian, 28 white, 2 Hispanic

Other demographics: high SES (81% moms, 90% dads had 4-year university degree; 84% moms, 90% dads employed; 68% families with annual income >$50 K)

Note: above appears to be descriptive of the 35 children recruited for the study, not the 30 children analyzed in the study

Summary of Results:

Energy intake

Doubling portion size of entrée increased entrée and total energy intake by 25% (p<=.001; n = 29) and 15% (p<=.01; n=29), respectively

Bite size and frequency

No difference in bite frequency by portion size
Increased bite size (12%) with large portion entrée (p<.05; n=29) (particularly for children who had ref portion sizes lunches before large portion lunches)
Self-served portions:
No difference due to intervention order (p=.37)
Self-served size not different from reference portion
Children consumed 24% more when served larger portion rather than when could self-serve from larger portion (p<.01; n=28)

BMI

No correlation with increases in entrée intake, total energy intake at lunch, bite size and self-served portion size with exposure to large portions
Positively related to mean bite size (p<.01)

Eating in absence of hunger

Positively related to increases in total energy intake at lunch with exposure to large portion size

Author Conclusion:

Large entrée portions may constitute an ‘obesigenic’ environmental influence for preschool-aged children by producing excessive intake at meals. Children with satiety deficits may be most susceptible to large portions. Allowing children to select their own portion size may circumvent the effects of exposure to large portions on children’s eating.

Previous studies showed that restrictive child-feeding strategies are associated with overeating and overweight in young children. At the other end of the continuum, however, the risk of overweight has been associated with neglectful family environments during childhood and with a lack of maternal knowledge of their children’s consumption of sweets.

Larger samples are needed to adequately evaluate the extent to which individual differences in susceptibility to portion size confer an increased risk of overweight.

Funding Source:

Government:

NIH

Industry:

Mars Inc

Food Company:

Reviewer Comments:

Strengths:

Subjects used as own controls;
methods well-described

Weaknesses:

Short-term study (no assessment of whether increased intake sustained across subsequent meals);
small samples size

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)	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?		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?	Yes
	2.4.	Were the subjects/patients a representative sample of the relevant population?	Yes
3.	Were study groups comparable?		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?	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?	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
4.	Was method of handling withdrawals described?		Yes
	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%.)	N/A
	4.3.	Were all enrolled subjects/patients (in the original sample) accounted for?	N/A
	4.4.	Were reasons for withdrawals similar across groups?	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
	5.1.	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.)	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
	5.5.	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?	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?	N/A
	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)?	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
	8.7.	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?	Yes
	10.2.	Was the study free from apparent conflict of interest?	Yes