Adolescence and young adulthood (12-25 years) represent critical developmental periods during which lifestyle patterns related to nutrition, physical activity, sleep, digital media use, social interaction, and stress regulation are consolidated and often persist into adulthood. Preventive interventions targeting these stages therefore offer substantial potential for long-term reduction of non-communicable disease (NCD) burden.
Although young people are often perceived as generally healthy, epidemiological evidence indicates a growing burden of NCD-related conditions in this population. Adolescent obesity has quadrupled in recent decades, affecting over 160 million children and adolescents worldwide (World Health Organization, 2021; Halilagic et al., 2025), and is strongly associated with increased risk of metabolic syndrome, type 2 diabetes, hypertension, cardiovascular disease (CVD), and certain cancers later in life (Shi et al., 2024).
A substantial body of evidence links obesity risk to modifiable lifestyle factors established early in life (Arnason et al., 2020; Zaman et al., 2019; Singh et al., 2025; Parvin et al., 2025), and behavioural interventions addressing these factors have demonstrated promising effects in young populations (Pastor et al., 2020; Ashton et al., 2019). However, existing interventions often show wide variability in design and outcomes and face persistent challenges related to long-term adherence, scalability, and equitable access (Melo et al., 2025; Talens et al., 2025). Many rely on professional-led delivery models requiring substantial human and financial resources, limiting their sustainability and reach, particularly in low-resource or geographically remote settings.
Digital health interventions have emerged as a promising means to improve accessibility and engagement while supporting self-monitoring and feedback. Digital approaches have demonstrated positive effects on behaviours related to physical activity, diet, and sleep (Singh et al., 2025). Nevertheless, many digital interventions remain largely individualised and screen-centric, insufficiently leveraging the social environments in which young people's behaviours are embedded, which may limit sustained engagement and long-term behaviour change.
In this context, peer mentoring represents a promising, yet, underutilised approach for strengthening behavioural self-management and primary NCD prevention among adolescents and young adults. Peer mentoring involves structured, supportive relationships in which individuals with shared or similar lived experiences provide guidance, encouragement, and role modelling. During adolescence and young adulthood, peers exert a strong influence on attitudes, norms, motivation, and behaviour. Peer-led approaches are often perceived as more relatable, credible, and emotionally safe than authority- or expert-led interventions, fostering trust, social connectedness, and intrinsic motivation (DuBois & Karcher, 2014; Smith et al., 2016). Peer mentoring programs have demonstrated effectiveness in promoting healthy behaviours and psychosocial outcomes in youth, particularly in school-based and community settings (Lavelle et al., 2023).
For these reasons, the aim of the current study will be to implement and evaluate a hybrid, human-delivered peer-mentoring intervention, combining in-person and remote interactions and supported by AI-informed tools that provide mentors with access to ethically governed, privacy-preserving participant indicators. More specifically, the intervention will include a structured school-based (adolescents) or campus- or community- based (young adults) behavioral change program delivered through peer-mentoring focusing on physical activity and nutrition in order to reduce obesity risk. The intervention' s content will be based on existing evidence-based interventions with a solid theoretical foundation (namely the Health Belief Model and Social Cognitive Theory). The program will recruit and appropriately train young mentors aged 14-25 years old. Mentors' training curriculum will be designed by experts in youth health (pediatrics, endocrinology), nutrition science, physiotherapy and behavioral science based on the aforementioned interventions and training will be performed through a pre-defined number of group sessions and is expected to be completed within a month. Subsequently, mentors will be matched with slightly younger peers (aged 12-23 years old) and they will deliver the intervention through structured weekly meetings and activities throughout the academic year. Each mentor-mentee pair will be supervised and supported by a qualified supervisor (psychologist or social worker) which will conduct regular meetings (twice a month) with each pair, will be available to support them during the study period and will ensure the program's implementation fidelity. The meetings and shared activities will take place at schools during the school curriculum for adolescents and at campuses or community centers for young adults. The program will be coordinated by a qualified professional which will support supervisors and will act as liaison between school and university personnel and supervisors.
