EAL

PWM: Foods and Nutrients (2006)

Citation:

Study Design:

Class:

- Click here for explanation of classification scheme.

Quality Rating:

Research Purpose:

To determine whether obese adolescents eat more high-calorie low-nutrient-dense (HC) foods than non-obese adolescents.

Inclusion Criteria:

Not specified, but convenience sample recruited from eight-control clinics and New England Medical Center and Children’s Hospital, Boston, MA, or were siblings or friends of subjects, employees’ children, or adolescents who had heard of the study.

Exclusion Criteria:

Of the 61 subjects in original 1990 study, 6 excluded due to incomplete diet records, 12 excluded because data not retrievable from obsolete mainframe computer.

Description of Study Protocol:

Subjects trained by RD to keep food diary using measuring cups and spoons and subsequently contacted 3-4 times during 14-day study to review.

Statistics:

Genders combined because no difference by ANOVA; Student’s t-test used to compared mean calories from high-calorie low-nutrient-dense foods, both reported and adjusted for under-reporting (assuming high-calorie low-nutrient-dense foods reported proportionate to other foods reported).

Data Collection Summary:

No blinding.

Dependent variables – body composition (doubly labeled water); measured weight and height

Independent variables – Intake:

Candy (chocolate and other)
Soda
Chips
Ice cream
Baked goods
(14-day food records)

Control variables – gender (examined, but no interaction), underreporting (adjusted high-calorie low-nutrient-dense calories based on difference in reported energy intake and expenditure [doubly labeled water])

Description of Actual Data Sample:

Sample:

21 obese (OB) boys (10) and girls (11); mean of 43% body fat
22 non-obese boys (10) and girls (12); mean of 21% body fat

Age: 12-18 years

Ethnicity: not specified

Other demographics: not specified

Summary of Results:

MACRONUTRIENTS – Obese subjects had greater percent % kcal from fat (p <.05) & protein (p<.05), less CHO (p<.001) (not adjusted for underreporting)

High-calorie low-nutrient-dense foods (total daily calories unadjusted for underreporting):

Chips: obese about the same as non-obese
Soda: obese about the same as non-obese
Candy: obese < non-obese
Baked goods: obese < non-obese
Ice Cream: obese < non-obese
Total HC calories: obese (20%) < non-obese (27%) (p<.01)

HC foods (total daily calories adjusted for underreporting)

Ice Cream: OB < non-OB (p<.05)
All other differences disappeared

Other foods:

Fruit drinks (juice + dinks): OB ˜ non-OB
Breakfast cereal: OB ˜ non-OB
Fruit (excluding juice): OB (0.4 svg/d) ˜ non-OB (0.6 svg/d)
Vegetable (excluding potatoes) OB (0.3 svg/d) ˜ non-OB (0.6 svg/d)

OB underreported significantly more than non-OB

Author Conclusion:

Our findings suggest that both non-obese and obese adolescents consume a substantial portion of reported calories from high-calorie low-nutrient-dense foods and that obese adolescents do not consume more calories from these foods than non-obese adolescents.

These data offer no evidence to support the widespread notion that obese adolescents eat more ‘junk food’ than non-obese adolescents. Health professionals who treat obese adolescents must be aware that the excess calories in their diets may come from a variety of food sources and not solely from high-calorie snack foods.

Funding Source:

Government:

NIH, NCRR

Reviewer Comments:

Strengths:

Adjusted for total calorie underrporting

Weaknesses:

Possibility of selective underreporting of high-calorie low-nutrient-dense foods by obese subjects,
no control for physical activity,
sufficient power?

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)	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?		No
	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?	No
	2.2.	Were criteria applied equally to all study groups?	No
	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?		No
	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?	No
	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?		No
	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)?	No
	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