Primary care literature emphasises the importance of agreement and shared models in the consultation. This study compared general practitioners' (GPs') and patients' models of obesity. Questionnaires concerning beliefs about the causes, consequences and solutions to obesity were completed by 89 general practitioners (GPs) and 599 patients from practices across UK. In terms of causes, the results showed that the patients were more likely to attribute obesity to a gland/hormone problem, slow metabolism and stress than the GPs, whereas the GPs were more likely to blame eating too much. In terms of consequences, the patients rated difficulty getting to work more highly whereas the GPs regarded diabetes as more important. For the solutions to obesity, the two groups reported similar beliefs for a range of methods, but whereas the patients rated the GP and a counsellor as more helpful, the GPs rated the obese person themselves more highly. It is argued that patients show a self serving model of obesity by blaming internal uncontrollable factors for causing obesity yet expecting external factors to solve it. In contrast, GPs show a victim blaming model by attributing both cause and the solution to internal controllable factors. Such differing models have implications regarding the form of intervention likely to be used in primary care and indicate that whereas patients would prefer a more professional based approach, GPs would prefer a more patient-led one. Further, the results suggest that even if an intervention could be negotiated, success rates would be low as either the patient or the GP would be acting in contradiction to their beliefs about the nature of obesity.