AbstractObjectiveTo identify Greek families in which all members were overweight or obese (XXL families) and to describe their profile with regard to their socio-economic status and their eating behaviours and practices.DesignA prospective cohort study.SettingThe metropolitan area of Kavala.SubjectsWe recruited children aged 11 and 12 years from twelve primary schools, and their parents, from volunteers. Auxologic measurements of the children included height and weight. A structured questionnaire pertaining to information on the socio-economic status of the family, anthropometric values and educational status of parents, dietary habits and the availability of various food products and beverages at home, as well as dietary intake, physical activity, time spent sleeping and time spent watching television, was filled in by one of the parents of each child. A total of 331 families finally participated.ResultsIn sixty-one families (18·43 %) both parents and child were either overweight or obese (XXL family), and in seven of these families all members were obese. Only twenty-eight families (8·46 %) had all members with a normal BMI. The XXL family was associated with lower educational status of both parents, whereas a higher percentage of XXL families resided in rural areas and had lower income. Skipping breakfast and spending more than 3 h in front of a screen every day were more frequently observed in XXL families. With regard to the availability of various food products and beverages at home, no significant differences were observed between XXL families and the rest of the studied families.ConclusionsGreek XXL families have lower educational status and lower annual income.