Obesity and other lifestyle-related illness are among the top healthcare challenges in Europe. Obesity alone accounts for up to 7% of healthcare costs in the EU, as well as wider economy costs associated with lower productivity, lost output and premature death. Obesity in younger age is an alarming predictor for obesity in adulthood, but also entails short term health complications in juvenile age along with greater risk of social and psychological problems.Knowing how to stay healthy is not enough to motivate individuals to adopt healthy lifestyles, but relevant progress can be achieved through the use of incentives delivered through a combination of processes and mobile technologies.Recognizing the effectiveness of this approach, the PEGASO project will develop a multi-dimensional cross-disciplinary ICT system that will exploit sophisticated game mechanics to motivate behavioral changes towards healthier lifestyles and prevent overweight and obesity in the younger population.The project relies on ICT technologies to implement a framework for the promotion of an health service based on three main features: individual&environmental monitoring, including wearable sensors, mobile phone and multimedia diaries for the acquisition of physical, physiological and behavioural attributes of participants; feedback to the user, presenting personalised healthy options for alternative lifestyles; social connectivity, encouraging involvement in social network experience sharing and social engagement. For the system development, a user centered approach, social and networked games and online education will be used. PEGASO will be tested with over 300 adolescents in three EU member states (Spain, Italy, UK).The development of PEGASO project will mobilize a wide stakeholders' ecosystem contributed by National Health Authorities and Research Institutions, Industries and Academia from the ICT and healthcare sectors, as well as food companies and SMEs