The distribution of the childhood obesity epidemic has spread all over the world in the last decades.1 To fight this worldwide problem, strategies to prevent childhood obesity2 and to detect and manage3 obese children must be developed. Genetic and environmental factors (diet and lifestyle) have been proposed as the main risk factors for childhood obesity development.4 Perinatal factors have also been involved in the pathogenesis of the condition.5 Complications of obesity are already present during childhood, and their frequency seems also to increase in the last years.6 All these aspects justify adequate prevention and management that would be adapted to specific groups, like morbid obese children or adolescents, when necessary.

All the commented aspects have been treated during the International Symposium ‘Childhood obesity: from basic knowledge to effective prevention’ and 14th Workshop of the ‘European Childhood Obesity Group’. From the beginning, the idea was to put together scientists and practitioners from very different fields in order to promote a multidisciplinary approach of the condition. An international perspective was considered desirable because the problem affects the worldwide paediatric population. The full papers of the lectures and all oral and poster abstracts have been included in this special supplement of the International Journal of Obesity and related metabolic disorders. It is important to note that abstracts from 19 countries have been presented. Of a total number of 86 abstracts, 27 came from Spain, eight from Australia, seven from the USA, five from Belgium, five from France, five from Sweden, four from Germany, and three from Japan, Cuba, Italy, and Austria, respectively; other countries presenting their abstracts were Algeria, Iceland, UK, Portugal, Poland, Greece, Russia, and Hungary. All these achievements would not be possible without the help of many European Childhood Obesity Group members, and especially our good friends from the actual ECOG Board, Kurt Widhalm, Inge Lissau, Carl-Erik Flodmark, and Angelo Pietrobelli.

In Zaragoza (Spain), at the University Department of Paediatrics and the corresponding Department at the University Hospital ‘Lozano Blesa’, childhood obesity research has been a priority for more than 25 y. These research activities have justified the support of the Spanish Ministry of Science and Technology and the University of Zaragoza (Spain). Without their help this supplement would not be possible. We strongly acknowledge their support. We also want to thank the people involved in the International Scientific Committee and the Local Organizing committee for their help and valuable inputs.

The following articles and abstracts represent the results of the Symposium's expositions.