Androgen deprivation therapy (ADT) in men with prostate cancer (PCa) is associated with significant side effects. With the transition of PCa from a foudroyant course to a chronic disease, managing these side effects has become increasingly important. There is growing evidence that nutritional changes and physical activity are beneficial in these patients. Here we examine the impact of written patient information on the physical activity and dietary habits of PCa patients receiving ADT and behaviour changes between baseline and 1 year, in the open-label, non-interventional LEAN study. In total, 959 patients with advanced hormone-sensitive PCa requiring ADT with the Leuprorelin Sandoz® implant were included from January 2014 to July 2015 and followed for ≥ 12 months. At the start of the study, urologists received a questionnaire concerning the written information provided to patients regarding their disease, patient advocacy groups, diet and physical activity. Patients received a questionnaire on their dietary habits and physical activity at the start and end of the study. Urologists from 147 study centres and 540 patients responded to the questionnaires. While 69 % of these patients received disease-specific information, only 30 % and 17 % received information regarding nutrition and physical activity, respectively. The majority of urologists estimate that their patients rarely or never follow guidance on nutrition or physical activity, yet > 90 % of patients indicate they would make use of this information, if provided. Few patients showed behavioural changes between baseline and 1 year without evident differences between patients that received information and those that did not.