Increase Font Size Decrease Font Size View as PDF Print

Winett RA, Roodman AA, Winett SG, Bajzek W, Rovniak LS, Whiteley JA. The effects of the Eat4Life Internet-based health behavior program on the nutrition and activity practices of high school girls. Journal of Gender, Culture, & Health. 1999;4(3):239-254.

Study Design:
Nonrandomized Controlled Trial
C - Click here for explanation of classification scheme.
NEUTRAL: See Research Design and Implementation Criteria Checklist below.
Research Purpose:

The Eat4Life program, consisting of Internet-based health behavior change modules on the topics of nutrition, fast food and aerobic exercise, was tested for efficacy in multiple groups of 9th and 10th grade girls.

Inclusion Criteria:
  • 9th and 10th grade
  • Female gender
  • Enrolled in high school health education classes
  • Attending one specific county high school in southwestern Virginia
  • Girls participating signed assent forms and their parents signed consent forms for the project
Exclusion Criteria:
  • Not in 9th or 10th grade
  • Male gender
  • Not enrolled in high school health education classes
  • Not attending the designated specific high school in southwestern Virginia
Description of Study Protocol:


Four 9th grade classes in the fall semester and four 10th grade classes in the spring semester participated in the study.

Design:  Nonrandomized controlled trial

  • The study consisted of two experimental and two comparison the grade classes in the fall and two experimental and two comparison 10th grade classes in the spring for a total of four separate replications of the program.
  • Experimental groups were assigned according to which classes had access to the school's computer lab.
  • Both experimental and comparison groups followed the same curriculum and had the same class instruction; the classes were 90 minutes in length.  The experimental class, in addition to the regular instruction, participated in five educational computer modules and additional experiential activities.
  • Measures were administered four times to both the experimental and comparison groups.  Two of the assessments for the experimental group were given by computer; all other assessments were paper and pencil and all questions were identical.
  • The same schedule was used to assess engagement in physical activity as well as fast food consumption.

Blinding used (if applicable):  not possible


The intervention group participated in an online educational module lasting 15-20 minutes and a short "primer experience" such as sampling a certain type of food.   The intervention modules were structured using social cognitive theory, using assessments and personal feedback through a series of interactions with the participant.

Statistical Analysis

For nutritional data and exercise data:

  • ANOVA for differences in experimental and respective comparison groups at pre-assessment
  • ANOVA for overall differenced in experimental and comparison groups (each combined) at pre-assessment
  • ANCOVA for target foods with pre-assessment score for each food as a covariate

For fast food data:

  • Information was only available in two spring experimental groups which were combined and analyzed with t tests.

For aerobic exercise data:

  •  ANCOVA for pre-assessment experimental and comparison and post-assessment experimental and comparison groups
Data Collection Summary:

Timing of Measurements

Measures were administered at four data collection points throughout the semester.  The assessment was given twice to the experimental group on the computer, otherwise all assessments were identical in content and given in paper and pencil format.

Dependent Variables

  • Nutrition outcomes
    • Increasing regular meals
    • Increasing servings of fruits and vegetables
    • Increasing servings of breads and cereals for fiber
    • Decreasing high-fat snacks
    • Decreasing high-fat dairy
    • Decreasing high-fat snacks
  • Fast food
    • Reducing total calories
    • Reducing fat grams
  • Aerobic conditioning activity
    • Increasing weekly frequency of exercise

Independent Variables

  • Eat4Life program modules

Control Variables

  • Both groups had the same curriculum and had the same class instruction. 
  • The experimental and comparison classes were taught at different times during the same school day.
Description of Actual Data Sample:

Initial N:

  • Experimental: N=103 girls
  • Comparison: N=77 girls

Attrition (final N):

  • Experimental: N=103
  • Comparison: N=77

Note:  Fast food and aerobic conditioning questions were added spring semester and only assessed in the experimental groups, where N=39.


  • 9th grade mean age:  14.9
  • 10th grade mean age:  15.9

Ethnicity:  Not noted

Other relevant demographics:

Typical parents of participants had a high school education and were employed in the service sector.


Location:  A county high school in southwestern Virginia

Summary of Results:

Key Findings:

  • Nutrition outcomes with ANCOVA with pre-scores as the covariate
    • Significant effects for:
      • increasing meals
      • increasing fruits and vegetables
      • increasing fiber
      • decreasing regular sodas
    • No significant effects for:
      • changes in high fat dairy
      • changes in snacks
  • Nutrition outcomes with ANCOVA with each pair of experimental and comparison classes
    • Significant effects for:
      • increasing meals--all four cohorts
      • fruits and vegetables-- all four cohorts
      • increasing fiber--three cohorts
      • decreasing soda--two cohorts
  • Fast food outcomes with t-test of reports in module two to reports in module five
    • Significant effects for:
      • decreasing calories in last fast food meal
      • decreasing fat grams in last fast food meal
  • Aerobic conditioning activity outcomes with ANCOVA for pre-assessment experimental and comparison and post-assessment experimental and comparison groups
    • Significant effects for:
      • increasing mean frequency of weekly aerobic conditioning

Nutrition outcomes:

Target Food Experimental
Pre Post
Regular meals, mean (SD)  2.3 (0.64)  2.6 (0.61)**
Fruits and vegetables, mean (SD)  3.5 (2.3)  4.6 (3.1)**
Breads and cereals, mean (SD)  2.6 (1.5)  3.6 (2.2)**
Regular soda, mean (SD)  2.0 (1.6)  1.3 (1.4)*
High-fat snacks, mean (SD)  3.4 (3.5)  2.8 (3.5)
High-fat dairy, mean (SD)  2.8 (2.2)  2.2 (2.3)


*ANCOVA = p < .05; ** = p < .001

There were no statistical differences in the comparison pre and post measures.

 Fast food:

Fast food details
Modules Test significance t-test
Reported module two Reported module five
Last fast food meal consumed kcals 1047 786 t(38) = 3.98**
Last fast food meal consumed fat grams 44.4 30.2 t(38) = 4.28**


** = p < .001

Aerobic conditioning activity:

Aerobic Conditioning Activity Experimental Comparison Test significance ANCOVA
Pre Post Pre Post
Mean days per week 3.15 3.80* 2.85 3.00 F(1,95) = 4.47*

 * = p<.05



Author Conclusion:

The Eat4Life program was in the short-term effective in helping four sets of 9th and 10th graders increase consumption of regular meals, fruits and vegetables, and fiber and decrease the consumption of regular sodas.  They also decreased their consumption of calories and fat from fast foods, and there is some evidence to suggest that they increased their frequency of exercise.

Reviewer Comments:
  • Non-randomization of classes was dictated by the access to computers.
  • Different teachers for the "experiment" and "comparison" classes could have some influence on students health knowledge, although the "experiment" group had the same modules as they were computer based.
  • Unknown demographic data across groups, other than age.
  • Any differences across groups of significance were not noted and assumed to be unknown.
  • Blinding was not possible due to presence of module or no module.  Unknown if teachers were blinded to objectives of the study.
  • Students at times did not have access to computers, possibly affecting outcomes.
  • The intervention module was changed in the spring semester by adding content and activities related to activity, exercise and fast food making the groups less comparable to prior groups.
  • In regards to participation it is noted:  "The participation rate among girls in the participating classes was close to 100%."
  • Food frequencies used in the assessments were self-reported introducing the possibility of error in accurate recall.

Research Design and Implementation 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)
  2. Did the authors study an outcome (dependent variable) or topic that the patients/clients/population group would care about?
  3. Is the focus of the intervention or procedure (independent variable) or topic of study a common issue of concern to nutrition or dietetics practice?
  4. Is the intervention or procedure feasible? (NA for some epidemiological studies)
Validity Questions
1. Was the research question clearly stated?
  1.1. Was (were) the specific intervention(s) or procedure(s) [independent variable(s)] identified?
  1.2. Was (were) the outcome(s) [dependent variable(s)] clearly indicated?
  1.3. Were the target population and setting specified?
2. Was the selection of study subjects/patients free from bias?
  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?
  2.2. Were criteria applied equally to all study groups?
  2.3. Were health, demographics, and other characteristics of subjects described?
  2.4. Were the subjects/patients a representative sample of the relevant population?
3. Were study groups comparable?
  3.1. Was the method of assigning subjects/patients to groups described and unbiased? (Method of randomization identified if RCT)
  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 used? (Concurrent preferred over historical controls.)
  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?
  3.5. If case control or cross-sectional 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. Criterion may not be applicable in some cross-sectional studies.)
  3.6. If diagnostic test, was there an independent blind comparison with an appropriate reference standard (e.g., "gold standard")?
4. Was method of handling withdrawals described?
  4.1. Were follow-up methods described and the same for all groups?
  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%.)
  4.3. Were all enrolled subjects/patients (in the original sample) accounted for?
  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?
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?
  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?
  5.5. In diagnostic study, were test results blinded to patient history and other test results?
6. Were intervention/therapeutic regimens/exposure factor or procedure and any comparison(s) described in detail? Were intervening factors described?
  6.1. In RCT or other intervention trial, were protocols described for all regimens studied?
  6.2. In observational study, were interventions, study settings, and clinicians/provider described?
  6.3. Was the intensity and duration of the intervention or exposure factor sufficient to produce a meaningful effect?
  6.4. Was the amount of exposure and, if relevant, subject/patient compliance measured?
  6.5. Were co-interventions (e.g., ancillary treatments, other therapies) described?
  6.6. Were extra or unplanned treatments described?
  6.7. Was the information for 6.4, 6.5, and 6.6 assessed the same way for all groups?
  6.8. In diagnostic study, were details of test administration and replication sufficient?
7. Were outcomes clearly defined and the measurements valid and reliable?
  7.1. Were primary and secondary endpoints described and relevant to the question?
  7.2. Were nutrition measures appropriate to question and outcomes of concern?
  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?
  7.5. Was the measurement of effect at an appropriate level of precision?
  7.6. Were other factors accounted for (measured) that could affect outcomes?
  7.7. Were the measurements conducted consistently across groups?
8. Was the statistical analysis appropriate for the study design and type of outcome indicators?
  8.1. Were statistical analyses adequately described and the results reported appropriately?
  8.2. Were correct statistical tests used and assumptions of test not violated?
  8.3. Were statistics reported with levels of significance and/or confidence intervals?
  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)?
  8.6. Was clinical significance as well as statistical significance reported?
  8.7. If negative findings, was a power calculation reported to address type 2 error?
9. Are conclusions supported by results with biases and limitations taken into consideration?
  9.1. Is there a discussion of findings?
  9.2. Are biases and study limitations identified and discussed?
10. Is bias due to study’s funding or sponsorship unlikely?
  10.1. Were sources of funding and investigators’ affiliations described?
  10.2. Was the study free from apparent conflict of interest?

Copyright American Dietetic Association (ADA).