New Zealand (NZ) has the highest rate of adult obesity in the region. Maori and Pacific men are at particularly high risk for overweight. A weight-management programme (Rugby Fans in Training; RUFIT-NZ) delivered by professional rugby clubs offers a viable and sustainable approach to engaging Maori and Pacific men in a healthy lifestyle programme. Building on a successful HRC feasibility study, we will conduct a randomised controlled trial of RUFIT-NZ to improve weight and health outcomes in overweight men. A total of 360 overweight men (aged 30 years or more) will be allocated at random to either receive the RUFIT-NZ programme delivered via professional rugby clubs or to a wait list control group. If effective RUFIT-NZ could be implemented relatively easily throughout all NZ rugby clubs and evaluates a delivery option with strong potential to improve health and reduce ethnic inequalities.