Each episode of Talk Evidence we take a dive into an issue or paper which is in the news, with a little help from some knowledgeable guests to help us to understand what it all means for clinical care, policy, or research.    In this episode: Helen Macdonald take a deep dive into cancer screening tests, prompted by a paper in JAMA which showed most have no effect on all cause mortality, and news that the NHS is evaluating a single test which screens for 50 common cancers - we ask Barry Kramer, former director of the Division of Cancer Prevention, at the U.S. National Cancer Institute to help explain how to hold those two pieces of knowledge. Juan Franco has been looking into diet and obesity, prompted by new research in The BMJ and a new Cochrane review, looking at the role of low glycemic index foods in weightloss - we ask Khadidja Chekima, nutritional researcher at Taylor’s University in Malaysia, to define low GI foods, and why it’s so hard to research their role in diet and weightloss    Reading list; JAMA research - Estimated Lifetime Gained With Cancer Screening Tests; A Meta-Analysis of Randomized Clinical Trials The BMJ news - Clinicians raise concerns over pilot of blood test for multiple cancers The BMJ research - Association between changes in carbohydrate intake and long term weight changes: prospective cohort study Cochrane review - Low glycaemic index or low glycaemic load diets for people with overweight or obesity