Abstract
Child nutrition has serious long-term development implications. Evidence-based frameworks and models are urgently needed to reduce deficits in infants and young children's diets on a large scale. Our paper reviews 32 publications and five impact evaluations of programmes in Bangladesh, Ethiopia, Nepal, Nigeria and Vietnam to identify what worked and why; the quality of evidence, diversity of countries and multi-level interventions on a large scale were selection criteria. Key lessons are: the need for advocacy to prioritize complementary feeding; engagement of multiple stakeholders to reach national scale and to address diverse factors such as food access, harmful marketing of unhealthy foods and beverages, knowledge gaps, social norms and maternal self-efficacy. Applying a behavioural science lens, monitoring intervention coverage, targeting to reduce inequalities, engaging community leaders, motivating frontline workers and leveraging mass media to reach multiple audiences worked synergistically to produce impacts at scale. Despite different contexts and dietary diversity levels at baseline, rigorous evaluations documented substantial improvements attributable to the interventions in all five countries. The expenditures incurred varied by programme complexity and showed that they are manageable if the interventions focus on priority issues, are streamlined to fit existing platforms and reach large populations. With evidence of impact in diverse contexts, an evidence-based conceptual framework and tools for implementation, insights into how to adapt to country contexts and knowledge of what to budget, decision-makers can invest confidently in improving complementary feeding programmes.