['Dietary supplements are not recommended as part of a weight-loss program due to concerns about efficacy and safety. This study sought to assess prevalence and duration of nonprescription weight-loss supplement use, associated weight-control behaviors, discussion of use with a health care professional, and specific ingredient use.', 'Adults aged > or =18 years (n=9,403) completed a cross-sectional population-based telephone survey of health behaviors from September 2002 through December 2002.', 'Both chi2 and t tests were conducted for categorical and mean comparisons and multiple variable logistic regression was used to determine significant predictors.', 'An estimated 15.2% of adults (women 20.6%, men 9.7%) had ever used a weight-loss supplement and 8.7% had past year use (women 11.3%, men 6.0%); highest use was among women aged 18 to 34 years (16.7%). In regression models, use was equally prevalent among race/ethnic groups and education levels. One in 10 (10.2%) of users reported > or =12 month use, with less frequent long-term use in women (7.7%) than men (15.0%), P=0.01. Almost one third (30.2%) of users discussed use during the past year; 73.8% used a supplement containing a stimulant including ephedra, caffeine, and/or bitter orange.'] Is use of nonprescription dietary supplements for weight loss common among Americans?