© 2017 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd. This is a protocol for a Cochrane Review (Intervention). The objectives are as follows: To determine the benefits and harms associated with weight loss in overweight individuals with knee or hip osteoarthritis in terms of pain, physical function, quality of life, and safety. Further we will have an explicit focus on quality of the weight loss intervention (including magnitude and intensity) (Herbert 2005), to see whether there is a dose-response relationship at the trial (i.e. group) level.