 Peanuts and tree nuts almonds, pistachios, walnuts, pecans, pine nuts, Brazil nuts, cashews, hazelnuts, macadamia nuts herein referred to as nuts are a good source of unsaturated fatty acids, vegetable protein, fibre, and polyphenolics. Nut intake has been associated with reduced cardiovascular disease risk and claims for this association have been permitted by the FDA; however, intake of tree nuts is low in Canada. One of the barriers to increasing the consumption of nuts is the perception that they may contribute to weight gain more than other healthy foods owing to their high energy density. The evidence supporting this concern, however, is lacking. In a series of earlier systematic reviews and meta-analyses, we have shown that nuts improve glycemic control and metabolic syndrome criteria, findings which run contrary to any expected weight gain. However, it remains unclear whether nuts have an increasing, neutral, or even decreasing effect on body weight. To address the uncertainties, the investigators propose to conduct a series of systematic reviews and meta-analyses of the totality of the evidence from controlled trials and prospective cohort studies to investigate the effect of nut consumption on body weight and adiposity. The findings generated by this proposed knowledge synthesis will help improve the health of consumers through informing evidence-based guidelines and improving health outcomes by educating healthcare providers and patients, stimulating industry innovation, and guiding future research design 