BACKGROUND:
The global surge in ultra-processed food (UPF) consumption is a major public health challenge, particularly among adolescents. UPFs, characterized by high energy density, added sugars, fats, and sodium, and low essential nutrients, are linked to poor diet quality and heightened risks of obesity, diabetes, and all-cause mortality. Despite growing concerns, there is limited evidence on school-based interventions targeting UPF reduction in low- and middle-income countries (LMICs) like India.

METHODS:
A cluster-randomized controlled trial was conducted across 12 public schools in Chandigarh, India, targeting Grade 8 adolescents and their parents. The intervention was structured around the PRECEDE–PROCEED Model and comprised eleven sessions for adolescents delivered over six months. Additionally, a single educational session was conducted for parents to enhance their awareness of reducing UPF consumption and encouraging healthier dietary behaviours. Dietary intake data were collected at baseline and end-line using two non-consecutive 24-hour dietary recalls. Foods were categorized based on NOVA food processing levels. The intervention's effectiveness was evaluated using a difference-in-differences analytical approach.

RESULTS:
The intervention significantly reduced UPF consumption among adolescents by 237 g/day (95% CI: -435, -38). However, no significant changes were observed in processed or minimally processed food consumption. Among parents, the intervention increased minimally processed food intake by 149 g/day (95% CI: 0, 299) but had no significant impact on UPF or processed food consumption. Process evaluation highlighted high participant engagement and feasibility of the intervention in school settings.

CONCLUSIONS:
This study demonstrates the potential of school-based behavioural interventions to reduce UPF consumption among Indian adolescents, addressing a critical gap in public health research and practice in LMICs.