The present study analyzes the prevalence of overweight/obesity in a sample of young adults from the University of the Basque Country (Spain), and tests the efficiency of the silhouettes to predict overweight/obesity. This cross-sectional study was conducted in a sample of volunteer university students from the University of the Basque Country (356 men and 745 women, age: 18-33 years), who came to the Physical Anthropology laboratory where a standardized questionnaire was administered and anthropometric measurements were taken by a well-trained anthropometrist. Height and weight were obtained. BMI was calculated as weight/height(2) (kg/m(2)) and it was used as a reference method. Using a questionnaire, based on the standard figural stimuli, subjects were asked to choose the silhouette which was closest to his/her usual appearance (current body size). The accuracy of the Williamson et al.'s silhouettes as an overweight-obesity indicator was analyzed by gender-specific receiver operating curve (ROC). The cutoff figure to distinguish between nonoverweight and overweight-obese individuals corresponded to number 7 in men and 6 in women. These cutoff values matched optimal sensitivity and specificity, with few nonoverweight subjects selecting silhouettes bigger than 7 in the case of men or 6 for women. In conclusion, the figural stimuli allows the identification of populations at overweight/obesity risk with the simple use of silhouettes, at least in this rank of age, where the overweight and obesity are yet little frequent.