Fast food and aggression: the theory comes from a group of Swedish nutritionists who have been studying the behaviour of schoolchildren in Aarhus since 1998. Considerable differences appear to have emerged between those who followed a diet based on natural foods and those who regularly ate at fast-food outlets. Hamburgers, chips and Coca-Cola are, according to the Swedish researchers, partly responsible for the aggression and poor academic performance of the latter. The case is cited of a young girl accustomed to drinking several litres of Coca-Cola a day and frequently eating hamburgers: a change in diet reportedly made her less aggressive and more focused on her studies.