BACKGROUND: Overweight and obesity are substantial problems in the U.S., but few national studies exist on primary care physicians' (PCPs') clinical practices regarding overweight and obesity. PURPOSE: To profile diet, physical activity, and weight control practice patterns of PCPs who treat adults. METHODS: A nationally representative survey of 1211 PCPs sampled from the American Medical Association's Masterfile was conducted in 2008 and analyzed in 2010. Outcomes included PCPs' assessment, counseling, referral, and follow-up of diet, physical activity, and weight control in adult patients with and without chronic disease and PCPs' use of pharmacologic treatments and surgical referrals for overweight and obesity. RESULTS: The survey response rate was 64.5%. Half of PCPs (49%) reported recording BMI regularly. Fewer than 50% reported always providing specific guidance on diet, physical activity, or weight control. Regardless of patients' chronic disease status, <10% of PCPs always referred patients for further evaluation/management and <22% reported always systematically tracking patients over time concerning weight or weight-related behaviors. Overall, PCPs were more likely to counsel on physical activity than on diet or weight control (p's<0.05). More than 70% of PCPs reported ever using pharmacologic treatments to treat overweight and 86% had referred for obesity-related surgery. CONCLUSIONS: PCPs' assessment and behavioral management of overweight and obesity in adults is at a low level relative to the magnitude of the problem in the U.S. Further research is needed to understand barriers to providing care and to improve physician engagement in tracking and managing healthy lifestyles in U.S. adults.