EAL

PWM: Eating Behaviors of Children (2006)

Citation:

Study Design:

Class:

- Click here for explanation of classification scheme.

Quality Rating:

Research Purpose:

To evaluate the effects of fast food on energy intake in overweight vs. lean adolescents. In Study One, the authors assessed energy intake during a fast food meal consumed in a naturalistic setting. In Study Two, the authors compared energy intake under free-living conditions on days when fast food was consumed and days when it was not consumed.

Inclusion Criteria:

Adolescents between 13 and 17 years of age who reported eating fast food at least once per week.
Lean: BMI below the 85th percentile.
At risk for overweight: BMI between the 85th and 95th percentiles.
Overweight: BMI above the 95th percentile.
At risk for overweight and overweight were grouped into a single overweight category.

Exclusion Criteria:

Adolescents with BMI below the 50th percentile or above the 98th percentile.
None were diagnosed with a medical illness or eating disorder, taking prescription medicine or dieting for weight loss.

Description of Study Protocol:

Recruitment

Newspaper advertisements and fliers.

Design

Study 1: Participants were grouped by sex and weight status to avoid any self- consciousness about eating that may be associated with these variables.
Study 2: Four dietary and physical activity recall interviews (two for fast food days and two for non-fast food days) were administered by telephone to assess energy intake under free-living conditions.

Statistical Analysis

Study 1: Two-sample T-tests (compare energy intake during the meal between overweight and lean adolescents).
Study 2: Analysis of variance using mixed linear modeling [examine whether the interaction between weight status and type of day (fast food vs. non-fast food days) influenced total energy intake].
Inter-study comparison: Mixed linear model (compare accuracy of self-report between overweight and lean participants).

Data Collection Summary:

Dependent Variables

Body mass index.

Independent Variables

Total energy intake (from fast food and non-fast food days).

Control Variables

Self-reported relative amount of food intake and meal size.

Description of Actual Data Sample:

Initial N

Attrition (final N)

Study 1: 54 (26 overweight, 28 lean)
Study 2: 51 (24 overweight, 27 lean).

Age

13 to 17 years.

Ethnicity

White: 35%
Non-white: 65%.

Location

Boston, Massachusetts.

Summary of Results:

Overweight adolescents tended to be less physically active than their lean counterparts (P=0.06) and tended to have a higher total energy expenditure (P=0.07).

Study One

When instructed to eat as much or as little fast food as desired, the participants consumed 1,652 (87) kcal, amounting to 61.6% (2.2%) of the estimated total energy expenditure.
Overweight participants ate more than lean participants, whether energy intake was expressed in absolute terms or relative to estimated needs.
Relative meal size ratings did not differ between the overweight and lean adolescents [8.5(0.4) vs. 7.8(0.5), P-0.22).

Study Two

Significant interaction between type of day (fast food vs. non-fast food day) and weight status (overweight vs. lean) for total daily energy intake (P=0.05 unadjusted, P=0.04 after adjustment for self-reported relative amount of food intake).
- Overweight participants consumed 409 (142) kcal per day more on fast food than non-fast food days.
- In contrast, energy intake was not significantly different on fast food and non-fast food days for the lean participants.
- With regard to physical activity, there was no interaction between type of day and weight status (P=0.46).
Recalled total daily energy intake, expressed as a percentage of estimated total energy expenditure, tended to be lower for the overweight compared with lean participants (-15.3% vs. 8.9%, P=0.09). Recalled energy intake from fast food in Study Two, compared with observed intake in Study One, was also lower for the overweight compared with lean participants (-17.3% vs. 8.7%, P=0.05). Adjustment for relative meal size rating in Study One did not materially affect this difference (-15.0% vs. 8.6%, P=0.09).
- Overweight participants tended to underreport total energy intake compared with lean participants. Group difference in reporting accuracy was similar for total and fast food energy intake (-15.3% vs. -17.3%, P=0.84), providing evidence against the possibility of a false positive result.

Author Conclusion:

Adolescents overconsumed fast food regardless of body weight, although this phenomenon was especially pronounced in overweight participants. Overweight adolescents are less likely to compensate for the energy in large portions of fast food than their lean counterparts. These findings do not imply that fast food is without detrimental effect in lean adolescents.

Funding Source:

Government:	NIDDK, NIH
University/Hospital:	Children’s Hospital, University of Minnesota

Reviewer Comments:

Strengths

Evaluation of energy intake in a naturalistic setting in Study One
Within-subject comparisons in Study Two, reducing the possibility of confounding by demographic and behavioral factors.

Limitations

Relatively small sample size
Restricted generalizability
Reliance on self-reporting for assessment of energy intake in Study Two.

Other Comments

Unclear: It appears that the 85th percentile is included in the “lean” category because it is stated that “adolescents with a BMI not exceeding the 85th percentiles were considered lean.”

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?		Yes
	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
	3.3.	Were concurrent controls or comparisons used? (Concurrent preferred over historical control or comparison groups.)	Yes
	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.)	Yes
	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?	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
	4.4.	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
5.	Was blinding used to prevent introduction of bias?		???
	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.)	???
	5.3.	In cohort study or cross-sectional study, were measurements of outcomes and risk factors blinded?	???
	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?	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?	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?	???
	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)?	N/A
	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?	Yes
	10.2.	Was the study free from apparent conflict of interest?	Yes