European energy balance research to prevent excessive weight gain among youth (ENERGY) project: design and methodology of the ENERGY cross-sectional survey

Maartje M. van Stralen, Saskia J. te Velde, Amika S. Singh, Ilse De Bourdeaudhuij, Marloes K. Martens, Maria van der Sluis, Yannis Manios, Evangelina Grammatikaki, Mai J.M. Chinapaw, Lea Maes, Elling Bere, Jørgen Dejgård Jensen, Luis Moreno, Natasa Jan, Dénes Molnár, Helen Moore, Johannes Brug