The habits of living are seen as important factors for public health, and are related to the primary socialization. Exercise and food habits are two main factors for development of health or ill health and are both related to the overweight epidemic. The overweight increase among children and youth has been given particular attention. The aim of this study is to examine how 15 year olds Body Mass Index, food- and exercise habits are connected to each other and also how they are related to socialization. The study is a cross sectional survey among 208 pupils in ninth grade, Kristianstad. 168 pupils were responding the questionnaire. The result showed less prevalence of overweight and higher prevalence of underweight than were expected. There emerged no connection between Body Mass Index and the pupil’s habits of living. On the other hand we found a strong connection between the primary socialization and habits of living. The study also shows a link between the different habits of living. We propose that public health work directed to children’s and youths in many ways should be focused on the primary socialization. We also want to attract more attention to the underweight among youths because of the indications that the prevalence is higher than expected.