Title: Transtheoretical model-based nutritional interventions in adolescents: a systematic review
Abstract: Abstract Background: Literature has shown a tendency of inadequate dietary intake among youth, consequently, nutritional interventions are required. The Transtheoretical Model (TTM) classifies individuals based on their readiness to change. This model is widely used for health education interventions with proven efficacy. Purpose: This review aimed to weigh the strength of evidence about the TTM usage in nutritional interventions for adolescents. Methods: The Adolec, Google Scholar, LILACS, PsycINFO, PubMed, Science Direct and Web of Science databases were searched. Only full original articles written in English, Spanish or Portuguese on randomized controlled trials and quasi-experimental designs that applied the TTM in the design of nutritional interventions targeting adolescents were included, with no restrictions on publication date. Results: The initial search yielded 3779 results. The final sample of 14 articles included adolescents that were mostly recruited from schools, with interventions ranging from one month to three years. The TTM was used alone or combined with other behavior-change theories and most of the interventions involved digital technology. The nutritional topics covered included fruit and vegetable consumption, low-fat diet, and cooking skills. Four studies presented improvement in fruit and vegetable consumption and also four progressed through stages of change. Participants from two interventions reduced fat intake. In other two interventions, participants presented weight loss. At the end of one intervention, all the participants were in action and maintenance stages. Conclusion: The TTM seems to be a successful strategy for nutritional intervention aiming at improving dietary intake in adolescents. Its application in different contexts shows that the TTM is flexible and possible to be implemented in many settings. The use of the model in the development of the intervention is shown to be restricted to the stage of change’ construct and focused on promoting a tailored intervention. Further studies comparing the TTM with other behavior-change theories should be conducted to better understand its effectiveness.