ISRCTN74109264.

Study name	Engaging adolescents in changing behaviour (EACH‐B): a programme of research to improve the diets and physical activity levels of adolescents
Methods	Type of trial: efficacy Allocation: cluster‐randomised Intervention model: parallel assignment Masking: open
Participants	Estimated number of schools: 50 Estimated number of students: 2300 Inclusion criteria (schools): state schools in Hampshire and surrounding areas Exclusion criteria (schools): single‐sex schools Inclusion criteria (students): aged 12 and 13 (Year 8) Exclusion criteria (students): ‐
Interventions	Intervention • Participation in LifeLab at the University of Southampton: a 3‐week science module linked to the National Curriculum, which helps teenagers think about science and their health • Encouragement from teachers trained to support students to improve their diets and exercise • A specially designed, interactive smartphone app that involves friends and has game features Comparator: no intervention
Outcomes	Primary outcomes: dietary quality, physical activity Secondary outcomes: well‐being, self‐regulation, body composition, compliance/adherence, self‐efficacy, use of digital intervention, teachers' competence, educational outcomes, cost Other outcomes: −
Starting date	Trial start date: January 2016 Trial completion date: March 2022
Contact information	Responsible Party/Principal Investigator: Dr. Sofia Strommer
Notes