title: A systematic literature review and meta-analysis: The Theory of Planned Behavior's application to understand and predict nutrition-related behaviors in youth.
abstract: BACKGROUND
  Efforts to reduce unhealthy dietary intake behaviors in youth are urgently needed. Theory-based interventions can be effective in promoting behavior change; one promising model is the Theory of Planned Behavior (TPB).
  
  
  OBJECTIVE
  The aim of this study was to determine, using a systematic literature review, how the TPB has been applied to investigate dietary behaviors, and to evaluate which constructs are associated with dietary behavioral intentions and behaviors in youth.
  
  
  METHODS
  Publications were identified by searching electronic databases, contacting experts in the field, and examining an evolving Internet-based TPB-specific bibliography. Studies including participants aged 2-18years, all TPB constructs discernible and measured with a description of how the variables were assessed and analyzed, were published in English and peer-reviewed journals, and focused on nutrition-related behaviors in youth were identified. Accompanying a descriptive statistical analysis was the calculation of effect sizes where possible, a two-stage meta-analysis, and a quality assessment using tenants from the Consolidated Standards of Reporting Trials (CONSORT) and Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) statements.
  
  
  RESULTS
  Thirty-four articles, including three intervention studies, were reviewed. The TPB was most often used to evaluate healthy eating and sugary snack and beverage consumption. Attitude had the strongest relationship with dietary behavioral intention (mean r=0.52), while intention was the most common predictor of behavior performance (mean r=0.38; both p<0.001). All three interventions revealed beneficial outcomes when using the TPB (e.g. η(2)=0.51 and ds=0.91, 0.89, and 0.79); extending the Theory with implementation intentions may enhance its effectiveness (e.g. η(2)=0.76).
  
  
  CONCLUSIONS
  Overall, the TPB may be an effective framework to identify and understand child and adolescent nutrition-related behaviors, allowing for the development of tailored initiatives targeting poor dietary practices in youth. However, support from the literature is primarily from observational studies and a greater effort towards examining these relationships within intervention studies is needed.
authors.affiliation: Department of Human Nutrition, Foods, and Exercise, Virginia Tech, 338 Wallace Hall, Mail Code: 0430, 295 West Campus Drive, Blacksburg, VA 24061, United States. Electronic address: sriebl@vt.edu.
authors.forename: Shaun K
authors.initials: SK
authors.lastname: Riebl
authors.affiliation: Department of Human Nutrition, Foods, and Exercise, Virginia Tech, 338 Wallace Hall, Mail Code: 0430, 295 West Campus Drive, Blacksburg, VA 24061, United States; Department of Family and Community Medicine, Carilion Clinic, 1 Riverside Circle, Suite 104, Roanoke, VA 24016, United States; Department of Statistics, Virginia Tech, 402 Hutcheson Hall, 250 Drillfield Drive, Blacksburg, VA 24060, United States. Electronic address: estabrkp@vt.edu.
authors.forename: Paul A
authors.initials: PA
authors.lastname: Estabrooks
authors.affiliation: Department of Family and Community Medicine, Carilion Clinic, 1 Riverside Circle, Suite 104, Roanoke, VA 24016, United States. Electronic address: jdunsmor@vt.edu.
authors.forename: Julie C
authors.initials: JC
authors.lastname: Dunsmore
authors.affiliation: Department of Psychology, Virginia Tech, 323 Williams Hall, Mail Code: 0436, United States. Electronic address: jsavla@vt.edu.
authors.forename: Jyoti
authors.initials: J
authors.lastname: Savla
authors.affiliation: Department of Human Nutrition, Foods, and Exercise, Virginia Tech, 338 Wallace Hall, Mail Code: 0430, 295 West Campus Drive, Blacksburg, VA 24061, United States. Electronic address: frisardm@vt.edu.
authors.forename: Madlyn I
authors.initials: MI
authors.lastname: Frisard
authors.affiliation: Department of Human Development, 237A Wallace Hall, Mail Code: 0426, Blacksburg, VA 24061, United States. Electronic address: andread@vt.edu.
authors.forename: Andrea M
authors.initials: AM
authors.lastname: Dietrich
authors.affiliation: Civil and Environmental Engineering/Food Science and Technology, Virginia Tech, 413 Durham Hall, 1145 Perry Street, MC 0246, Blacksburg, VA 24061-0246, United States. Electronic address: yiming09@vt.edu.
authors.forename: Yiming
authors.initials: Y
authors.lastname: Peng
authors.affiliation: Civil and Environmental Engineering/Food Science and Technology, Virginia Tech, 413 Durham Hall, 1145 Perry Street, MC 0246, Blacksburg, VA 24061-0246, United States. Electronic address: xiang@vt.edu.
authors.forename: Xiang
authors.initials: X
authors.lastname: Zhang
authors.affiliation: Department of Human Nutrition, Foods, and Exercise, Virginia Tech, 338 Wallace Hall, Mail Code: 0430, 295 West Campus Drive, Blacksburg, VA 24061, United States. Electronic address: bdavy@vt.edu.
authors.forename: Brenda M
authors.initials: BM
authors.lastname: Davy
mesh_terms: D000293:Adolescent; D001290:Attitude; D002648:Child; D002675:Child, Preschool; D004032:Diet / Q000523:psychology*; D015438:Health Behavior; D006801:Humans; D033182:Intention; D011582:Psychological Theory; D016032:Randomized Controlled Trials as Topic
keywords: Diet; Eating behaviors; Nutrition; Theory of planned behavior; Youth