Highlights
A cluster-randomised controlled trial involving 12 public schools in Chandigarh, India, has demonstrated that a structured behaviour change intervention can significantly reduce the intake of ultra-processed foods (UPFs) among adolescents. The primary findings indicate a reduction in UPF energy intake by 1062 Kcal/day and processed food intake by 274 Kcal/day. The intervention, grounded in the PRECEDE-PROCEED model, proved both feasible and engaging, though it showed limited efficacy in altering parental dietary habits through a single session.
The Rising Tide of Ultra-Processed Foods in LMICs
The global nutritional landscape is undergoing a rapid transition, characterized by the displacement of traditional diets by ultra-processed foods (UPFs). These products, defined by the NOVA classification system as industrial formulations containing little to no whole foods and various additives, are engineered for hyper-palatability and long shelf-life. In low- and middle-income countries (LMICs) like India, this shift is particularly concerning among adolescents, a demographic vulnerable to peer influence and aggressive marketing.
Chronic consumption of UPFs is strongly associated with adverse health outcomes, including childhood obesity, metabolic syndrome, and early-onset type 2 diabetes. Despite the clear public health imperative, there has been a paucity of evidence-based interventions tailored for the socio-economic and cultural contexts of schools in the Indian subcontinent. The study by Kaur et al. addresses this critical gap, providing a blueprint for school-based nutritional advocacy.
Study Design and Methodology
The researchers employed a cluster-randomised controlled trial (cRCT) design, which is the gold standard for evaluating public health interventions in institutional settings. Twelve public schools in Chandigarh were selected and randomly assigned to either the intervention or control group. The study focused on Grade 8 students and their parents, acknowledging that while adolescents are gaining autonomy, the home environment remains a secondary influencer of dietary choices.
The PRECEDE-PROCEED Framework
The intervention was uniquely structured around the PRECEDE-PROCEED model, a comprehensive planning framework for health education. This approach allowed the researchers to address three critical constructs:
- Predisposing factors: Increasing knowledge and altering attitudes toward UPFs.
- Enabling factors: Providing the skills and environmental cues necessary to choose healthier alternatives.
- Reinforcing factors: Creating a supportive social norm within the school and home to sustain behavioural changes.
Over a period of six months, students participated in 11 interactive sessions. These sessions were designed to be more than just lectures; they included hands-on activities, label-reading workshops, and discussions on the impact of food marketing. Parents were also included via a single educational session aimed at increasing awareness of the NOVA food categories and the health risks associated with processed items.
Data Collection and Analysis
To measure the impact, the study utilized two non-consecutive 24-hour dietary recalls at both baseline and endline. Energy levels were estimated using data from the Prospective Urban Rural Epidemiology (PURE) study, adapted for the Indian context. The primary outcome was the change in energy intake from foods categorized by the NOVA system. The researchers applied a difference-in-difference (DiD) analytical approach to account for any underlying trends and to isolate the true effect of the intervention.
Key Findings: A Significant Impact on Caloric Intake
The results of the trial are striking. Adolescents in the intervention group showed a substantial decrease in their daily energy intake from UPFs compared to the control group. Specifically, the intervention led to a reduction of 1062 Kcal/day (95% CI -2100 to -67). This reduction represents a significant portion of the total daily energy requirement, suggesting that the intervention successfully replaced calorie-dense, nutrient-poor foods with other options or reduced overall overconsumption.
In addition to the reduction in UPFs, there was a notable decrease in the consumption of ‘processed foods’ (NOVA group 3) by 274 Kcal/day (95% CI -526 to -23). Interestingly, the consumption of minimally processed foods (NOVA group 1) did not show a statistically significant change. This suggests that while students successfully avoided industrial snacks and sodas, there is still work to be done in proactively increasing the intake of whole foods like fruits, vegetables, and legumes.
Parental Involvement and Secondary Outcomes
A secondary objective of the study was to evaluate the impact on parental dietary habits. However, the data revealed no significant change in the energy intake of parents across any of the NOVA categories. The researchers hypothesize that the single educational session provided to parents was insufficient to overcome long-standing dietary habits and the logistical challenges of household food procurement. This finding underscores the difficulty of influencing adult behaviour through school-based programs and suggests that more intensive, multi-modal strategies are required for the home environment.
Clinical and Public Health Implications
For clinicians and public health experts, this study provides several actionable insights. First, it confirms that schools are a viable and effective venue for behavioural change in India. The process evaluation noted high engagement levels, suggesting that adolescents are receptive to nutritional education when it is delivered through interactive and theoretically grounded frameworks.
Second, the scale of the reduction in energy intake—over 1000 Kcal—is clinically significant. If sustained, such changes could drastically reduce the risk of obesity and metabolic disorders in this population. However, the lack of shift toward minimally processed foods indicates that future interventions should not only focus on ‘what to avoid’ (UPFs) but also place a stronger emphasis on ‘what to include’ (whole foods).
Expert Commentary and Limitations
While the findings are promising, several limitations must be considered. The reliance on 24-hour dietary recalls is subject to recall bias and social desirability bias, where participants might under-report ‘unhealthy’ foods. Furthermore, the study was conducted in public schools in an urban setting; its generalizability to private schools or rural areas, where food access and socio-economic dynamics differ, remains to be seen.
The NOVA classification system itself, while widely used, is sometimes criticized for focusing on processing rather than traditional nutrient profiles. However, in the context of this study, it served as a clear and effective tool for teaching adolescents how to identify industrial food products. The biological plausibility of the results is supported by the fact that reducing UPFs naturally leads to a reduction in free sugars and unhealthy fats, which are the primary drivers of excess caloric intake.
Conclusion
The Chandigarh cRCT demonstrates that a structured, behaviour-based school intervention can successfully curtail the consumption of ultra-processed foods among adolescents in India. By utilizing the PRECEDE-PROCEED model, the study addressed the multi-faceted drivers of dietary choice. While parental change remains a challenge, the success among students offers a powerful tool for public health policy. Scaling such interventions could be a cornerstone in India’s strategy to combat the burgeoning epidemic of non-communicable diseases.
Funding and Clinical Trial Registration
This study was supported by local health research funds and academic grants. The trial is registered with the Clinical Trials Registry – India (CTRI), registration number: CTRI/2019/09/021452.
References
Kaur S, Kumar R, Kaur M. School-based behaviour change intervention to reduce ultra-processed food consumption among adolescents: evidence from a cluster-randomised controlled trial in India. BMJ Glob Health. 2026 Jan 9;11(1):e020799. doi: 10.1136/bmjgh-2025-020799. PMID: 41513306; PMCID: PMC12815165.
