Although obesity used to be confined largely to high income countries, the proportion of people who are overweight or obese is now increasing globally. Obesity is a major risk factor for a number of chronic diseases, which have negative consequences for individuals, populations, and health service costs. We searched the scientific literature for randomised controlled trials that compared routine care with interventions that aimed to change either the way health professionals worked to achieve weight loss in overweight and obese people or interventions that aimed to change the organisation of care for them. We examined the effects of interventions targeting the behaviour of health professionals or the way care is organised, with the aim of improving the management of overweight and obese people in primary care, outpatient and community settings. Our review found six relevant trials, assessing more than 246 health professionals and 1324 patients. One of these trials reported that issuing doctors with reminders about weight management strategies helped to reduce their patients' weight; one trial found that dietitian or doctor plus dietitian led weight-loss programmes were more efficient than routine care. One trial found no evidence that either mail or phone interventions were better than standard care in reducing patients' weight.Three trials looked at brief training packages for doctors, but their findings were not consistent. All the included studies varied in terms of participants, interventions, outcomes, and settings. Consequently, we cannot draw any firm conclusions about the effectiveness of these interventions.