Second  International  Workshop  on  Behavior  Change  Support  Systems  (BCSS  2014)   17   A Persuasive System for Obesity Prevention in Teenagers: a Concept Maurizio Caon1, Stefano Carrino1, Renata Guarnieri2, Giuseppe Andreoni2, Claudio L. Lafortuna3, Omar Abou Khaled1, and Elena Mugellini1 1 University of Applied Sciences and Arts Western Switzerland, Fribourg {Maurizio.Caon,Stefano.Carrino,Omar.AbouKhaled,Elena.Mugellini} @hes-so.ch 2 Politecnico di Milano, Italy Giuseppe.Androni@polimi.it,Renata.Guarnieri@fondazione.polimi.it 3 Consiglio Nazionale delle Ricerche, Milan, Italy Claudio.Lafortuna@cnr.it Abstract. In the frame of the PEGASO European project, we aim at creating an ecosystem that enables teenagers to easily adopt a healthy lifestyle. In this ecosystem, the persuasive ICT system plays a key role in motivating users to build healthy habits. The persuasive system is based on mobile technologies and provides tailored motivational mechanisms based on the information pro- vided by the virtual individual model. Keywords: persuasive technology, obesity prevention, computer-tailored in- tervention. 1 Introduction Lifestyle has been identified as the main preventive methods for several health risks. Among the main emerging problems overweight at all ages ranks probably at first place. But if for adults this could be a result of a joint pathology, in teen- ager counter fighting overweight with proper strategies could be a win-win model for a real prevention of future pathologies. Overweight could also easily become Obesity, which is now epidemic in many countries so that a general alarm has been issued worldwide. Obesity is due to several factors as genetic contributors, metabolic conditions (e.g. diabetes and hypertension), psychological and behav- ioral issues. Concerning the last two factors, an important role is played by an inadequate education [1], in particular about health literacy. We faced the promo- tion of healthier lifestyles in an ongoing European project (PEGASO) aiming at developing a complete services ecosystem that would be able to motivate teenag- ers to learn and to apply a healthy life-style effortlessly. This ecosystem compre- hends many actors as the school system, the teenagers’ family, the social com- munity, the medical experts and other stakeholders. The creation of this ecosys- tem aims at enabling the teenagers, who are not fully independent in their life to facilitate the adoption of a healthy life-style. 18   Second  International  Workshop  on  Behavior  Change  Support  Systems  (BCSS  2014)   2 Virtual Individual Model The ICT system plays a key-role in the PEGASO ecosystem. The influence that technology can exercise on people is recognized by the scientific community and currently a new domain in the computer science, known as Persuasive Technolo- gy [2], focuses on formalizing the design and development of computing products that can change the way users act and think. In the persuasive technology field, the Behavior Change Support Systems became an important object of studies since this name describes the persuasive systems that integrate additional soft- ware features as continuous accessibility and social support, unobtrusiveness, ease of use, and improved dialogue between the users and the system [3]. The PEGASO project aims at pushing this concept further introducing the feature of dynamically selecting the opportune tailored interventions based on the user’s individual characteristics and interaction context. Tailoring the intervention in- volves modeling the user’s characteristics and for this purpose it has been devel- oped the Virtual Individual Model, which comes from the concept of the Virtual Physiological Human. The latter is a methodological and technological frame- work for integrated modeling of a living human body that describes the interac- tion of all the physiological components of individuals from molecular to appa- ratus level [4]. The Virtual Individual Model aims to include individual’s charac- terization composed of physiological, physical, and psychological determinants. This allows integrating biological aspects of human functioning with lifestyle behaviors and psychosocial externalities that are crucial for the determination of the adoption of a certain life-style. This model is integrated in the system through an ontology-based virtualization. This process allows turning the information contained in the Virtual Individual Model into a structured knowledge that can be dynamically updated and elaborated by the computer to select the best interven- tions for each individual. Tailored interventions make the information personally relevant and researches demonstrated that computer-tailored health education is more effective in motivating people to make dietary changes [5] and that it could be also a good practice to promote physical activity [6]. 3 Tailored Intervention Forms The Virtual Individual Model characterizes the user’s nutritional habits, physical status, and psychological status to provide personalized intervention to foster the adoption of a healthy life-style. Obviously, the interaction between the system and the user plays a crucial role in the tailoring process and to facilitate the effec- tiveness of the intervention. Since the teenagers are the targets of the PEGASO project, the smartphone has been chosen as the mediator of the interaction. In- deed, the smartphones are already perceived as a companion and it is most likely that this relationship between user and smartphone will strengthen in the future [7]. The smartphone is the perfect companion because it is personal and it is ubiquitous. It will provide the possibility of interacting directly with the user asking to enter some information or in a discreet and implicit manner allowing monitoring the user activity. The sensed data referring to the parameters that con- Second  International  Workshop  on  Behavior  Change  Support  Systems  (BCSS  2014)   19   cern the selected characteristics modeled for the tailoring will be updated con- stantly in the Virtual Individual Model. Moreover, with the many connection possibilities, the smartphone can allow accessing the information stored in the cloud and can connect to other devices, such as wearable accessories that can improve the physical activity monitoring. Since it is ubiquitous, it can always provide the appropriate trigger, as tailored messages, to influence the user’s be- havior. This is very important, since Fogg observed that “without an appropriate trigger, behavior will not occur even if both motivation and ability are high” [8]. Moreover, the many sensors integrated in the smartphone allow capturing the contextual information, which can help to generate the trigger at the opportune moment maximizing its effectiveness. Moreover, the smartphone allows in- stalling many applications as media services and games that will motivate the teenagers to interact with the system. The mobile game will be designed to pro- mote physical exercise. The integration with social networks will add the social aspect of the users’ life to the parameters for the tailoring of the interventions and, most importantly, the social factor represents a very effective motivator. Another mobile application will be a sort of personal food diary, where the user will be able to note his/her alimentary behavior. This diary will help to under- stand the alimentary behavior of the user in order to provide the right feedback. For example, some data suggest that breakfast consumption is associated with higher intakes of micronutrients, fruit and vegetables and less frequent use of soft drink [9]. This means that the breakfast consumption habit can help to adopt a healthy dietary behavior. The diary allows following this behavior and to inter- vene through an alarm in order to remind to the teenager to have breakfast. The eating behavior is not only related to homeostatic reasons. In fact, an important factor that influences people’s need and choice of food is represented by the emo- tional state [10]. The diary will allow noting also the mood in order to include the emotional state in the recognition of behavioral patterns. In fact, this information can be used to find some specific behavioral pattern related to emotional eating in order to generate the best intervention. 4 Conclusion Currently, the PEGASO project is in the design phase, where all the experts from the different domains are working to create the cross-disciplinary Virtual Individ- ual Model with the related ontology for the digitalization. At the same time, some participants coming from the Psychology, the Industrial Design and the Computer Science domains are conducting focus groups and participatory design events in schools in three different countries (Italy, Spain and United Kingdom) for the design of the system. In a later stage when the system will be developed, three pilots in different countries will take place (Italy, Spain and United Kingdom). These pilots will allow validating the effectiveness of this approach and examin- ing the cultural differences that may impact on teenagers' life-style. The discus- sion of the future development of this system with the experts that will attend the workshop will provide the possibility of generating an interesting debate and to receive important feedback from different points of view. 20   Second  International  Workshop  on  Behavior  Change  Support  Systems  (BCSS  2014)   References 1. C. Weinert, S. Cudney, and E. Kinion, “Development of My Health Companion to enhance self-care management of chronic health condi- tions in rural dwellers.,” Public Health Nurs., vol. 27, no. 3, pp. 263–9, 2001. 2. Fogg, B. J. (2002). Persuasive technology: using computers to change what we think and do. Ubiquity, 2002(December), 5. 3. Oinas-Kukkonen, H. (2013). 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