Aim: The aim was to extend the body of knowledge through a systematic review that combines the strengths and partly fills the gaps from earlier reviews. The aim is to review randomized controlled trials of the long-term effectiveness of physical exercise/activity with or without diet and/or behaviour modification therapy in terms of training effect, weight loss and improvement of body composition in overweight and obese, healthy adults.Methods: Data for systematic review was collected via a search of databases for literature published between 1995 and 2006. The search yielded 12 articles.Results: The studies showed that training intensity should be moderate. The treatment of overweight and obese individuals with training alone cannot be expected to result in any substantial weight loss but should be combined with diet and behaviour modification therapy. However training can be an important factor in preventing further weight gain, or in helping individuals maintain a lowered body weight.Conclusion: According to this systematic review of randomized controlled trials, the treatment that produced the best weight loss results included a combination of training, behaviour therapy and diet.