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Long JD, Stevens KR. Using technology to promote self-efficacy for healthy eating in adolescents. J Nurs Scholarsh. 2004; 36: 134-139.

PubMed ID: 15227760
Study Design:
Non-Randomized Controlled Trial
C - Click here for explanation of classification scheme.
NEUTRAL: See Research Design and Implementation Criteria Checklist below.
Research Purpose:

The aims of the study were:

  • To test the effects of a classroom and World Wide Web (WWW) educational intervention on self-efficacy (SE) for healthy eating (HE), dietary knowledge, usual food choices and food consumption
  • To examine the relationship of the theoretical concepts in a hypothesized model of eating behavior in adolescents.
Inclusion Criteria:
  • Adolescents in the seventh, eighth or ninth grades
  • Able to read and write responses on the questionnaires
  • Access to the World Wide Web (WWW).
Exclusion Criteria:
  • Did not have eating disorders
  • Did not have learning difficulties.
Description of Study Protocol:


A random sample of 121 adolescents from the seventh, eighth and ninth grades met study criteria. Volunteer students in two schools were assigned by the researcher as the Intervention and Comparison Groups. 


Group non-randomized trial.


  • The classroom intervention consisted of a combination of five hours of web-based instruction and 10 hours of classroom curriculum, compared to nutrition-education embedded in the standard school curriculum during a one-month period. The web-based nutrition was divided into three modules:
    • "Treasure Hunt: A Quest for the Golden Orb"
    • "Sampler: Ruby's Cafe"
    • "Web-Quest Diet and Life-Long Health"
  • Students discovered answers at their own pace, interacted with their peers and linked to web health education sites that used a gaming approach to nutrition education. The nutrition education designed for the study was based on the integrative review of literature and consideration of the social and developmental preferences of adolescents to increase SE for HE to affect dietary behavior. Written protocols and training were provided to faculty and school staff members involved in the study
  • Participants completed six questionnaires: Three focused on fat and sodium intakes, two focused on knowledge and fruits and vegetables and confidence to increase fruits and vegetables intake and one focused on measuring the average daily servings fruits, vegetables, and fats. The six questionnaires were:
    • "Dietary SE for lower fat and sodium" (reported internal consistency of 0.84 and alpha coefficient in this study of 0.85)
    • "Usual food choice," focused on high fat and salt vs. lower fat and lower salt (reported internal consistency of 0.85 and alpha coefficient in this study of 0.89)
    • "Which is better for your health," focused on dietary knowledge of lower fat and salt (reported reliability coefficient of 0.75 and alpha coefficient in this study of 0.95)
    • "Fruit-Vegetable SE scale," focused on the students' confidence in their ability to consume fruits and vegetables (reported alpha coefficient of 0.91 and alpha coefficient in this study of 0.90)
    • "Youth and Adolescent food frequency questionnaire," focused on measuring (not tested for internal consistency)
    • "Gimme 5 Dietary Knowledge for Fruits and Vegetables questionnaire," focused on dietary knowledge of fruits and vegetables (reliability for this study was 0.55)
  • The classroom curriculum was provided by four science teachers. The curriculum was behaviorally oriented, activity-based and designed to provide students with the knowledge, skills and attitudes to enable them to adopt eating behaviors
  • Students in the comparison school received the nutrition education embedded in the health, science and home economics curriculum.

Statistical Analysis

  • Data were analyzed using descriptive statistics, T-tests and Pearson's correlation coefficients
  • A two-tailed alpha level of significance was established at P<0.05, except an alpha level of <0.10 was selected for the "Better for Your Health Scale" to decrease the possibility of making a Type 1 error based on a violation of homogeneity.
Data Collection Summary:

Timing of Measurements

  • Self-efficacy for healthy eating, usual food choices, dietary knowledge and dietary intakes of fruits, vegetables and fat were measured at baseline and one month later in both the intervention and comparison groups
  • The six questionnaires to measure eating behaviors were administered in the same sequence at both pre- and post-test in both schools to minimize the potential for students to base their responses on what they thought was healthy for them or what others wanted them to do. 

Dependent Variables

Differences between group means were tested for:

  • Self-efficacy for healthy eating
  • Dietary knowledge of lower fat intake
  • Usual food choices
  • Fruit, vegetable and fat consumption.

Independent Variables

  • Intervention group
  • Comparison group.

Control Variables

Teacher effect.

Description of Actual Data Sample:
  • Initial N
    • Overall: 121 (52% female, 48% male)
    • Intervention: 63 (31 males, 32 females)
    • Comparison: 58 (27 males, 31 females)
  • Attrition (Final N): 121 students
  • Age: 12 to 16 years old (mean, 13 years old)
  • Ethnicity: 47% white, 42% Hispanic, 11% black
  • Anthropometrics: None
  • Location: San Antonio, Texas.
Summary of Results:

Key Findings

  • Students in the Intervention Group had higher self-efficacy for fruits and vegetables, self-efficacy for lower fat (P<0.001), usual food choices (P<0.001) and dietary knowledge of fat, compared to the Comparison Group (P<0.01)
  • No significant differences were found between groups in food consumption
  • Self-efficacy was significantly associated with dietary knowledge of lower fat (P<0.05), usual food choices (P<0.001) and was inversely associated with lower-fat consumption in the hypothesized model of eating behaviors
  • No association was found between self-efficacy for fruits and vegetables and consumption of fruits and vegetables. 

Other Findings

  • Adolescents in each group ate less than the five servings of fruits (mean, 1.9) and vegetables (mean, 1.9) and more dietary fat than recommended
  • A statically-significant difference between teachers was found in regard to student knowledge of lower fat, saturated fat and lower sodium choices (P<0.05). Two teachers had students with significantly higher mean scores for dietary knowledge for fat.
Author Conclusion:
  • Students in the Intervention Group had higher self-efficacy for healthy eating, more dietary knowledge and healthier usual food choice scores than did those in the Comparison Group. The results did not indicate a significant change in eating behavior in the intervention school
  • The hypothesized model of eating behavior indicates that adolescents need sufficient self-efficacy for healthy eating to make healthy choices and to be willing and capable of executing in a variety of environments before generating a change in eating behavior. The findings of this study supported the association between increased self-efficacy for healthy eating for lower fat, usual food changes and lower fat consumption
  • In summary, the intervention was tailored to the social and developmental preferences of adolescents and effectively increased self-efficacy for healthy eating.
Reviewer Comments:

A strength of the study included that students were encouraged to go to Internet links that offered a gaming approach to learning. Peer interaction and positive feedback indicated a high level of enjoyment with this method.The computer-based method of interaction was a developmentally appropriate means of providing nutrition education with adolescents.

Limitations of study include:

  • Limitations with resources influenced the use of a pre- and post-test FFQ to estimate changes in eating behavior. Measurements of food consumption may not have been sufficiently sensitive to detect a significant change in eating behavior
  • The intervention consisting of 10 hours of classroom and five hours of Web-based nutrition education over a month may not have been long enough for a significant change in food consumption. A longer period of exposure to the intervention may have resulted in a measurable change in eating behavior
  • The sample was limited to a random selection of students from two schools volunteering to participate in the study. Thus, the results may not be generalizable
  • Low reliability of the questionnaire to measure dietary knowledge of fruits and vegetables.
  • Intervention did not include environmental, family, and community-based strategies for supporting sustained eating behavior changes among adolescents.

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).