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IntroductionGlobally, over 1.97 billion adults and 338 million children and adolescents are living with overweight and obesity, increasing the risk of numerous co-morbidities, including at least 12 cancers(1). WCRF/AICR conducted a literature review of diet and physical activity as determinants of weight gain, overweight and obesity in adults and children. We also introduce a novel evidence-based policy framework for promoting physical activity, and linked database, currently in development as part of the EU-funded CO-CREATE project on child and adolescent obesity prevention.Materials and MethodsEvidence on diet and physical activity as determinants and risk of weight gain, overweight and obesity was systematically extracted from existing reviews and a systematic search for recent meta-analyses, then collated and analysed. The WCRF Continuous Update Project Expert Panel drew conclusions about which exposures influence risk of weight gain, overweight and obesity, using pre-defined criteria that included evidence of biological plausibility.ResultsThe Panel identified strong evidence that several diet and physical activity related exposures influence the risk of weight gain, overweight and obesity in adults and children (see table 1). Separate conclusions were drawn for adults and children in relation to screen time, considered a marker of sedentary time.However, the Panel noted that as exposures tend to cluster, physiologically interact and share common biological mechanisms, they should not be regarded as absolutely ‘singular'but an integrated concept of interrelated exposures within a pattern of lifestyle. Table 1.Risk of weight gain, overweight and obesitySTRONG EVIDENCEDECREASES RISKINCREASES RISKCONVINCINGWalkingScreen time (children)Sugar sweetened drinksPROBABLEAerobic physical activityFoods containing dietary fibre‘Mediterranean type’ dietary patternHaving been breastfedScreen time (adults)‘Fast foods’‘Western type’ dietFor full list of footnotes, see Energy Balance and Body Fatness report(1).DiscussionHealthy dietary patterns help prevent excess weight gain. Achieving such patterns requires attention to the broader economic, environmental and social factors that influence and constrain people's behaviour. The findings of this report support the need for evidence-based public health policy to help create health-enabling environments, particularly for children and adolescents. The WCRF International MOVING framework(2) presents a package of policies to promote physical activity, which alongside wider public health policy can help address the multiple drivers of overweight and obesity.

Introduction Understanding the causes of cancer depends on synthesising epidemiological, clinical and mechanistic evidence. Using this approach, the 2007 WCRF/AICR Expert Report defined the likely causal contributions of factors related to food, nutrition and physical activity to cancer risk, based on systematic literature reviews (SLRs) of evidence published up to 2005. For the Continuous Update Project (CUP) a team at Imperial College London (ICL) updates the previous databases as new studies are published. Methods The CUP follows a similar process to the 2007 Expert Report. Having first combined the separate databases for the 17 cancers reviewed for the 2007 Expert Report into one database, the ICL team conducts SLRs of links between food, nutrition physical activity and specific cancer sites, and displays and analyses the evidence according to peer-reviewed protocols. An independent expert panel draws conclusions based on the updated evidence. The database is currently being updated with papers published since 2005 through a rolling programme. A complete, continuously updated database is expected by 2015. Results An updated SLR for breast cancer was consistent with the conclusions of the 2007 Expert Report. Further reports of updated SLRs will be published on other cancers. Once the SLRs for all the cancer sites have been updated, the database will be made publicly available, and the 2007 Expert Report recommendations reviewed. Conclusion The CUP will provide a unique resource synthesising epidemiological and other evidence on food, nutrition, physical activity and cancer, to facilitate related research, and underpin advice to public and policy-makers.