1. Department of Gastroenterology, Digestive Diseases and Surgery Institute, Cleveland Clinic London, London SW1X 7HY, UK
2. Centre for Obesity Research, University College London, London WC1E 6BT, UK
3. Division of Surgery and Interventional Science, University College London, London NW3 2PS, UK
4. Bariatric Centre for Weight Management and Metabolic Surgery, University College London Hospital, London WC1E 6BT, UK
5. Biomedical Research Centre, University College London Hospital, National Institute of Health Research, London WC1E 6BT, UK
6. Department of Diabetes and Metabolism, Barts Health Trust, London EC1A 7BE, UK