Several studies suggested that patients with advanced Parkinson's disease (PD) showed a too low body weight when compared with age-matched, healthy subjects. We aimed to investigate whether PD patients with dyskinesias display body weight alterations and to observe any correlations between medication and other putative determinants. Charts of 166 PD patients with fluctuations and dyskinesias, admitted within 6 months to a German movement disorders clinic, were investigated for body mass index (BMI), age at onset, disease duration, Unified Parkinson's Disease Rating Scale motor score, eating coordination and medication. Analysis showed that 4.2% of PD patients were underweight (BMI < 18.5 kg/m(2)), 46.4% were normal (BMI > 18.5-25 kg/m(2)), 33.7% were overweight (BMI > 25-30 kg/m(2)), 15.7% were obese (BMI > 30 kg/m(2)). Daily levodopa dosage per kg and total dopaminergic dosage per kg body weight were negatively correlated with BMI. Overall, patients' BMI had not significantly changed within 2 years of follow-up. In sum, advanced PD patients showed a reduced BMI when compared with a control population obtained from an age-matched group taken from a survey of the German Federal Office for Statistics. Our findings indicate that patients with a lower BMI received a higher cumulative levodopa dosage and that levodopa may be responsible for weight loss in PD.