Patients with bipolar disorder are at increased risk of weight gain, which in turn, increases the risk for somatic disease and non-adherence to maintenance therapy. Therefore, interventions addressing weight gain are expedient for the management of this disorder. The investigators set out to evaluate the effects of a lifestyle intervention on body mass index, cardiovascular, glycemic and metabolic parameters in patients with bipolar disorder under mood stabilizing pharmacological treatment. 50 outpatients with bipolar disorder under mood stabilizing treatment participated in a randomized controlled trial (waiting control group N=24 and multimodal lifestyle intervention N=26). Each experimental group consisted of two cohorts. The intervention lasted five months and consisted of eleven group sessions and weekly fitness training. Body Mass Index (BMI), body weight as well as cardiovascular, glycemic and metabolic parameters were determined as baseline (March and September 2005) and after five (July 2005 and January 2006) and eleven months (January and July 2006).