BRCA1/2 mutation carriers have a considerably increased risk to develop breast and ovarian cancer during their lifetime. There is evidence from the literature that for sporadic breast cancer disease risk and the course of disease can be significantly influenced by physical activity, nutrition and weight. The hypothesis of this 3 year, prospective randomized multicenter efficacy trial is that a structured life-style intervention program with exercise training and mediterranean diet is effective regarding increased adherence to a mediterranean diet, reduction of body mass index, and increase of physical fitness.