New research suggests that four billion people globally will be overweight in 2050. This trend can be traced back to the ‘low-fat, high-carb’ guidelines first issued in the 70s, and should prompt a major U-turn on dietary advice. A recent report from the Potsdam Institute predicts that by 2050 there will be four billion overweight people in the world, with one-and-a-half billion of them obese. This is not entirely surprising. The world has been getting fatter for years, and things do not seem to be slowing down. This Organisation for Economic Cooperation and Development (OECD) graph, which looks at the rise in overweight adults in a number of different countries, shows that the trend seems inexorably upward.