Prevention of Eating Habits Associated With Obesity in Adolescents Through a Wise Intervention
Phase: NA
Conditions: Obesity, Adolescent, Eating, Healthy
Sponsor: University of Deusto

Prevention of Eating Habits Associated with Obesity in Adolescents through a Wise 
Intervention 
Project 
February 21, 2023 
 
 
 
Participants: 
Esther Calvete, Izaskun Orue, Ainara Echezarraga, Liria Fernández y Nerea Cortazar  
University of Deusto 
David Yeager y Christopher Bryan 
University of Texas, Austin 
Cintia Hinojosa  
University of Chicago 
 
 

 
Justification for the Project 
Obesity in adolescence is associated with physical and mental health problems and predicts 
obesity in adulthood. Adolescence may be an ideal time to target interventions, as this is when 
numerous health-related habits are consolidated (Bryan et al., 2019). Several universal 
preventive interventions have been carried out in educational centers for the promotion of 
healthy eating habits. However, the results of reviews and meta-analyses have concluded that 
most are not cost-effective for producing long-term changes in the dietary preferences of young 
people (Ashton et al., 2019; Kobes et al., 2018).  
Why Do Traditional Interventions with Adolescents Fail?  
Traditional interventions typically include nutrition education strategies and tell adolescents 
what behaviors they should and should not engage in (Steinberg, 2015). However, some 
characteristics of adolescence can cause these approaches to fail. If adolescents perceive that 
adults are trying to manipulate them or introduce behavioral patterns such that their autonomy 
is threatened, they will often resist (Yeager et al., 2018).  
The so-called wise interventions paradigm is an innovative approach to interventions that 
involve a set of rigorous techniques grounded in research to help people improve in a variety of 
life settings (Walton & Wilson, 2018). In recent years, a proliferation of wise interventions has 
achieved significant results in addressing social and personal problems, such as depression, 
stress, and other health problems. Furthermore, this type of intervention is of great interest to 
adolescents as it is designed in a way that is perceived as respectful of adolescents’ autonomy 
and status (Yeager et al., 2018).  
Recently, Bryan et al. (2016, 2019) developed a wise intervention aimed at improving 
adolescents’ daily dietary choices. Their intervention, called the values alignment intervention, 
focused on the role of marketing on the behavior of children and adolescents who are exposed 
to a relentless barrage of marketing from the food industry. This marketing strategy is designed 
to reinforce the positive value of junk food and increase its consumption. Therefore, many 
experts have pointed to marketing as a key risk factor for unhealthy eating in the general 
population (Harris et al., 2009). 
The values alignment intervention seeks to neutralize the positive emotional associations with 
junk food that marketing generates and presents the rejection of unhealthy foods in favor of 
healthy alternatives as a way to live up to two values that are important to adolescents: (1) the 
desire to be autonomous from adult control, and (2) the desire for social justice (Bryan et al., 
2019). In two randomized controlled trials, this team demonstrated that the intervention 
reduced implicit positive associations with junk food and substantially improved dietary choices, 
especially in boys (Bryan et al., 2016, 2019). In addition, there were significant differences in 
attitudinal variables related to healthy eating. These promising results suggest that reframing 
unhealthy eating as incompatible with important youth values could be a low-cost solution to 
produce changes in adolescent attitudes and dietary choices. 
Project Objectives  
The general objective of this project is to adapt the values alignment intervention to improve 
obesity-related eating habits in Spanish adolescents. It is therefore a highly innovative project 
with great potential for social impact in the field of health promotion. The specific objectives 

are: (1) to adapt the values alignment intervention to the Spanish culture and context, (2) to 
evaluate the effects of the intervention in reducing unhealthy food intake and increasing 
healthy food intake in adolescents, (3) to evaluate differences between adolescents receiving 
the intervention and those in the control group regarding attitudinal variables related to 
healthy eating (alignment of healthy eating habits with adolescents' values and social 
attractiveness of healthy eating), (4) to evaluate potential moderators of the effect of the 
intervention, specifically socioeconomic status, given that more disadvantaged socioeconomic 
levels are associated with worse eating habits and greater obesity, gender, given that in the 
study by Bryan et al. (2019) the effect was more beneficial in boys, and body mass index (BMI), 
given that those adolescents with a higher BMI may present more consolidated habits of 
unhealthy food consumption, and (6) to evaluate whether the effect of the intervention on 
eating behavior is mediated by attitudinal variables. 
Methodology  
Sample: The study will be carried out with adolescents in the second and third years of high 
school in Bizkaia (Spain). The necessary estimated sample size is 500, under a small, 
anticipated effect size (0.2), a statistical power of 0.8, and a probability level of 0.05. In 
anticipation of a loss of participants during the follow-ups, the sample size will be increased to 
600. Inclusion criteria include adequate reading comprehension and parental and self-
informed consent.  
Design and Procedure: A randomized controlled trial with two groups will be used. 
Randomization will be done by clusters, using the classroom as the unit. First, the schools will 
be selected according to their characteristics. Then, for each school and grade, half of the 
classrooms will be randomly assigned to the experimental condition (values alignment) and 
the other half to the control condition (traditional educational intervention). Participants will 
complete an online assessment protocol using Qualtrics, which will be composed of different 
questionnaires at three time points: (1) pretest (immediately before the intervention), (2) 
posttest (one week after the intervention), and (3) a three-month follow-up. The study has the 
approval of the Ethics Committee of the University of Deusto. The trial will be registered on 
ClinicalTrials.gov. 
Interventions: The experimental group will receive the values alignment intervention (Bryan et 
al., 2016). This includes: (1) reading materials, such as recent journalistic works that expose the 
deceptive and manipulative marketing practices of food companies and the harmful effects of 
these practices on society, with particular emphasis on harm to young children and the 
economically disadvantaged. Stories from other young people will also be included in order to 
contribute to the perception of widespread outrage and to suggest how that outrage can be 
channeled into taking a stand against the injustice perpetrated by food companies by eating 
less unhealthy or healthier food, (2) writing exercises, such as a story with a brief statement of 
what the participants would tell a younger child about the ads, and (3) an interactive activity, 
called "Make It Real" in which they are shown pictures of food ads and allowed to write and 
draw about them, making whatever changes (e.g., crossing out and substituting words) they 
feel necessary to make the ad "real" (i.e., no longer misleading). The control group will receive 
a traditional educational intervention on nutrition and physical exercise. This will be of the 
same duration and will also include reading and writing exercises. 
Measurements: Healthy and unhealthy food intake will be measured at pretest, posttest, and 
three-month follow-up using the questionnaire developed by Stok et al. (2015). It consists of 

four items that provide an index of unhealthy eating. In addition, according to the content 
addressed in the intervention sessions in the posttest and three-month follow-up, two 
attitudinal variables will be evaluated: (1) the alignment of healthy eating habits with the 
values of adolescents using seven items from Bryan et al. (2019), and (2) the social 
attractiveness of healthy eating using three items from Bryan et al. (2019), and answered on a 
five-point scale. Finally, some individual characteristics will be measured through an ad hoc 
questionnaire: gender, age, socioeconomic status (education and parental profession), height, 
and weight (to determine BMI). 
Statistical Analysis: To evaluate the effect of the intervention on the repeated measures of the 
dependent variables, a multilevel analysis with MPLUS-8.8 will be used. This will include 
repeated measures at level one (e.g., healthy and unhealthy food intake), adolescent variables 
at level two (assigned intervention and potential moderators), and the classroom at level 
three. It will be determined whether the intervention explains the slope of change of the 
dependent variables (intervention × time interaction). For moderation effects, triple 
interaction terms will be created using dummy variables or z variables, depending on the 
nature of the variables. To assess whether the effect of the intervention on healthy and 
unhealthy food intake is mediated by the attitudinal variables, a structural equation model 
with a bootstrapping procedure will be estimated (N = 10,000 samples). For the handling of 
missing values, the full information maximum likelihood method will be used as a general 
approach, although, depending on the nature of the missing value patterns, other techniques 
(e.g., multiple imputations or use of auxiliary variables) may be used. 
BUDGET 
Concept 
Amount 
Contract for a research assistant with a degree in psychology on a part-time basis (25 
hours per week).  
20,000 
Travel and per diem expenses for researchers Christopher Bryan and David Yeager for 
coordination and adaptation of the intervention materials for Spanish adolescents. 
6,100 
Incentive vouchers for participants. Vouchers will be raffled among the participants in 
each classroom to encourage participation. These will have a value of 20 euros and can 
be exchanged in shopping centers. Two vouchers will be raffled in each of the 
approximately 30 classrooms.  
1,200 
Trips to schools. 
1,100 
Expendable materials, such as markers and paints for intervention activities, which will be 
given to the adolescents.  
1,600 
Total 
30,000  
QUARTERLY WORK PLAN 
1 
2 3 
4 
1. Adaptation of the materials for Spanish adolescents 
x 
 
 
 
2. Acquisition of materials 
x 
 
 
 
3. Training the research staff on the procedures  
x 
 
 
 
4. Contacting schools and obtaining permissions 
x 
 
 
 
5. Application of pretest and intervention measures 
x 
x 
x 
 
6. One-week and three-month follow-ups 
 
x 
x 
 
7. Merging and cleaning of databases 
 
 
x 
 
8. Statistical analysis of data  
 
 
x 
x 
9. Writing the final report and scientific manuscripts 
 
 
 
x 
10. Dissemination and transference in conferences, participating schools, and 
society in general 
 
 
 
x 

References 
Ashton, L. M., Sharkey, T., Whatnall, M. C., Williams, R. L., Bezzina, A., Aguiar, E. J., ... & Hutchesson, M. 
J. (2019). https://doi.org/10.3390/nu11040825 
Agencia Española de Seguridad Alimentaria y Nutrición, AESAN. (2019). Recuperado de: 
https://www.aesan.gob.es/AECOSAN/web/nutricion/detalle/aladino_2019.htm 
Bryan, C. J., Yeager, D. S., & Hinojosa, C. P. (2019). https://doi.org/10.1038/s41562-019-0586-6 
Bryan, C. J., Yeager, D. S., Hinojosa, C. P., Chabot, A., Bergen, H., Kawamura, M., & Steubing, F. (2016). 
https://doi.org/10.1073/pnas.1604586113. 
Hale, D., Fiztgerald-Yau, N., Viner, R. (2014). https://doi.org/10.2105/AJPH.2014.301874 
Harris, J. L., Pomeranz, J. L., Lobstein, T., & Brownell, K. D. (2009). doi: 
10.1146/annurev.publhealth.031308.100304 
Kobes, A., Kretschmer, T., Timmerman, G., & Schreuder, P. (2018).  https://doi.org/10.1111/obr.12688  
López-Sobaler, A. M., Aparicio, A., Salas-González, M. D., Loria Kohen, V., & Bermejo López, L. M. 
(2021). https://dx.doi.org/10.20960/nh.3793 
Payne, K., & Lundberg, K. (2014). https://doi.org/10.1111/spc3.12148 
Steinberg, L. (2015). https://doi.org/10.1177/1745691615598510 
Stice, E., Shaw, H., & Marti, C. N. (2006). https://doi.org/10.1037/0033-2909.132.5.667 
Stok, F. M., de Vet, E., de Wit, J. B., Luszczynska, A., Safron, M., & de Ridder, D. T. (2015). 
https://doi.org/10.1017/S1368980014001268 
Walton & Wilson TD. (2018). doi:10.1037/rev0000115 
Wang, Y. C., McPherson, K., Marsh, T., Gortmaker, S. L., & Brown, M. (2011).  
http://doi.org/10.1016/S0140-6736(11)60814-3 
Yeager, D. S., Dahl, R. E., & Dweck, C. S. (2018). https://doi.org/10.1177/1745691617722620