Twenty parkinsonian patients will be randomised : the delay between inclusion and neurostimulation wil be lengthened 3 months for one group, compared to the second one. The energy expenditure, at rest and after ingestion of a test meal, will be compared between the group of patients that had been neurostimulated and the group whose intervention has been postponed. Weight changes, energy intake, leptin level, neurophysiological parameters will be compared between both groups, and the nature and repartition of the weight gain will be assessed in the neurostimulated group. An eventual link between motor factors, pharmacological factors, and gain weight will be studied.