Unrealistic weight-loss goals may impede the success of weight-loss attempts. The aim of this study was to examine the frequency of unrealistic goals and their association with other patient characteristics at the start of a weight-loss program. For patients with a body mass index (calculated as kg/m(2)) of 30 to 35, 35 to 40, or 40 to 50, medically advised weight-loss goals were set at 10%, 15%, and 20% of current weight, respectively. Personal weight-loss goals exceeding the medically advised goal by >50% were considered unrealistic. Obesity-related beliefs were measured by the "Obesity Cognition Questionnaire" and the eating-behavior self-efficacy scale of the "Obesity Psychosocial State Questionnaire." From September 2003 until March 2006, 90 patients were enrolled in the study, 26 men and 64 women, with a mean age of 43 years (range=18 to 68 years) and body mass indexes ranging from 30 to 50. Unrealistic goals were observed in 49% of the patients and were more frequent in younger patients (P=0.03), in patients attributing their obesity to physical causes (r=0.35, P=0.001), and in patients not attributing their obesity to behavioral causes (r=-0.28, P=0.008). This study confirms that discrepancies in weight-loss goals between obese patients and professionals occur frequently. Because unrealistic goals can hamper long-term outcomes of weight-loss programs, better outcomes could possibly be achieved by addressing unrealistic weight-loss goals before treatment.