1. Centre for Obesity Northern Netherlands, Department of Surgery Medical Center Leeuwarden Leeuwarden The Netherlands
2. Department of Biomedical Science University of Groningen Groningen The Netherlands
3. Department of Internal Medicine Catharina Hospital Eindhoven Eindhoven The Netherlands
4. Department of Management Tilburg University Tilburg The Netherlands
5. Department of Internal Medicine Spaarne Hospital Hoofddorp The Netherlands
6. Department of Endocrinology University of Groningen, University Medical Center Groningen Groningen The Netherlands