This systematic review was commissioned by the NHS R&D Health Technology Programme on behalf of the National Institute of Clinical Excellence (NICE). The views and opinions expressed do not necessarily reflect those of the NHS Executive.

The authors are grateful to the advisory panel who provided expert advice and comments for an earlier version of this systematic review (Clegg 2002):
Professor JN Baxter (Department of Surgery, Swansea), Professor B Campbell (Consultant General Surgeon, Exeter), Dr I Campbell (NOF Chairman, Nottingham), Sir A Cuschieri (Professor of Surgery, Dundee), Professor P James (Chairman, International Obesity Task Force, London), Professor R Jung (Consultant Physician, Chief Scientist to Scottish Executive, Dundee), Mr J D B Miller (Consultant Surgeon, Elgin), Dr AM Mir (University of Wales College of Medicine, Cardiff), Ms M O'Kane (Chief Dietician, Leeds), Mr P Sedman (Consultant Surgeon, Hull), Dr JPH Wilding (General (Internal) Medicine, Liverpool).

Also, we would like to thank the following people for information:
Ms L Hodson (Information Service, Wessex Institute for Health Research and Development), Dr A Avenell (Health Services Research Unit, Aberdeen), Dr J Baird (Specialist Registrar in Public Health Medicine, Southampton).