• Malnutrition has long been researched and addressed in two distinct silos, focusing either on chronic 2 or acute undernutrition, energy inadequacy and micronutrient deficiencies, or on overweight, obesity 3 and dietary excess. The contemporary reality of the double burden of malnutrition is different, making it 4 impossible to separate these issues, but also indicating shared opportunities to address them. 5 • Malnutrition harms health throughout the life-course, but its emergence early in life has particularly 6 pernicious consequences. A variety of physiological mechanisms propagate effects of early-life 7 malnutrition across the life-course, while adolescent and adult malnutrition can transmit effects to the 8 next generation. 9 • Different forms of malnutrition can interact through the life-course and across generations. In some 10 settings, early stunting may predispose to a more central distribution of adiposity at later ages, while 11 the extent to which maternal obesity adversely affects early growth and development of the offspring 12 may be exacerbated if the mother herself was under-nourished in early life. 13 • Life-course exposure to the double burden of malnutrition (early undernutrition followed by later 14 overweight) increases the risk of non-communicable disease, by imposing a high metabolic load on a 15 depleted capacity for homeostasis. The health costs of adult obesity are therefore exacerbated among 16 those who previously experienced undernutrition. In women, life-course exposure to the double burden 17 of malnutrition increases the risk of childbirth complications. 18 • Exclusive and appropriate breast-feeding protects infants against all forms of malnutrition, and 19 protects mothers against diabetes and breast cancer, in part through healthy-weight benefits. However, 20 maternal obesity, diabetes and micronutrient deficiencies alter the biology of lactation, and should be 21 addressed to maximise the success of breast-feeding. 22 • Exposure to the double burden of malnutrition can only be fully understood in the context of broader 23 societal drivers acting across culture, behaviour and technology. Various groups are at high risk of the 24 double burden through elevated exposure to these drivers, often exacerbated by biological 25 susceptibility. 26 • Developmental responses to malnutrition in early life are shaped by ecological factors, such as 27 pathogen burden and extrinsic mortality risk. An evolutionary perspective, focusing on how our 28 biological plasticity was shaped in ancestral environments to promote survival and reproduction, may 29 help design interventions that promote linear growth and lean tissue accretion rather than excess 30 adiposity. 31 • Inter-generational cycles of malnutrition have proven difficult to disrupt through public health 32 interventions. Major societal shifts are required regarding nutrition and public health, in order to 33 implement comprehensive change that is sustained over decades, and scaled up into the entire global 34 food system.

Multi-component behaviour-changing interventions that incorporate diet, physical activity and behaviour change may be beneficial in achieving small, short-term reductions in BMI, BMI z score and weight in children aged 6 to 11 years. The evidence suggests a very low occurrence of adverse events. The quality of the evidence was low or very low. The heterogeneity observed across all outcomes was not explained by subgrouping. Further research is required of behaviour-changing interventions in lower income countries and in children from different ethnic groups; also on the impact of behaviour-changing interventions on health-related quality of life and comorbidities. The sustainability of reduction in BMI/BMI z score and weight is a key consideration and there is a need for longer-term follow-up and further research on the most appropriate forms of post-intervention maintenance in order to ensure intervention benefits are sustained over the longer term.

IntroductionGenerating country-level political commitment will be critical to driving forward action throughout the United Nations Decade of Action on Nutrition (2016–2025). In this review of the empirical nutrition policy literature, we ask: what factors generate, sustain and constrain political commitment for nutrition, how and under what circumstances? Our aim is to inform strategic ‘commitment-building’ actions.MethodWe adopted a framework synthesis method and realist review protocol. An initial framework was derived from relevant theory and then populated with empirical evidence to test and modify it. Five steps were undertaken: initial theoretical framework development; search for relevant empirical literature; study selection and quality appraisal; data extraction, analysis and synthesis and framework modification.Results75 studies were included. We identified 18 factors that drive commitment, organised into five categories: actors; institutions; political and societal contexts; knowledge, evidence and framing; and, capacities and resources. Irrespective of country-context, effective nutrition actor networks, strong leadership, civil society mobilisation, supportive political administrations, societal change and focusing events, cohesive and resonant framing, and robust data systems and available evidence were commitment drivers. Low-income and middle-income country studies also frequently reported international actors, empowered institutions, vertical coordination and capacities and resources. In upper-middle-income and high-income country studies, private sector interference frequently undermined commitment.ConclusionPolitical commitment is not something that simply exists or emerges accidentally; it can be created and strengthened over time through strategic action. Successfully generating commitment will likely require a core set of actions with some context-dependent adaptations. Ultimately, it will necessitate strategic actions by cohesive, resourced and strongly led nutrition actor networks that are responsive to the multifactorial, multilevel and dynamic political systems in which they operate and attempt to influence. Accelerating the formation and effectiveness of such networks over the Nutrition Decade should be a core task for all actors involved.

Children and adolescents with overweight and obesity are a global health concern. This is an integrative overview of six Cochrane systematic reviews, providing an up-to-date synthesis of the evidence examining interventions for the treatment of children and adolescents with overweight or obesity. The data extraction and quality assessments for each review were conducted by one author and checked by a second. The six high quality reviews provide evidence on the effectiveness of behaviour changing interventions conducted in children <6 years (7 trials), 6-11 years (70 trials), adolescents 12-17 years (44 trials) and interventions that target only parents of children aged 5-11 years (20 trials); in addition to interventions examining surgery (1 trial) and drugs (21 trials). Most of the evidence was derived from high-income countries and published in the last two decades. Collectively, the evidence suggests that multi-component behaviour changing interventions may be beneficial in achieving small reductions in body weight status in children of all ages, with low adverse event occurrence were reported. More research is required to understand which specific intervention components are most effective and in whom, and how best to maintain intervention effects. Evidence from surgical and drug interventions was too limited to make inferences about use and safety, and adverse events were a serious consideration.

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