This study examined a new method of providing brief, individual lifestyle modification to obese individuals treated by pharmacotherapy. Twenty-six women with a mean (+/- SD) age of 47.0 +/- 7.2 years, weight of 97.6 +/- 13.0 kg, and body mass index of 36.5 +/- 5.0 kg/m2 were prescribed 60 mg/d of fenfluramine and 15 mg/d of phentermine for one year. In addition, half of the women were randomly assigned to traditional group behavior modification, conducted by a nutritionist, which included 32 75-minute sessions during the year. The other half were provided lifestyle modification by a physician during 10 15-20 minute structured visits. All participants received identical treatment manuals and comparable assignments for behavior change. At the end of one year, patients in the physician group achieved the same highly successful weight losses as those treated by group behavior modification (13.9 +/- 9.6 kg vs. 15.4 +/- 7.9 kg, respectively). Treatment was associated with highly significant improvements in lipids and lipoproteins, as well as in mood and several measures of appetite. Weight loss the first four weeks, as well as patient completion of daily food records during the first 18 weeks, correlated positively with weight loss at weeks 18, 26, and 52. Results of this study await replication using larger samples but strongly suggest that effective lifestyle modification can be provided during brief, structured physician visits. The findings are discussed in terms of their implications for the treatment of obesity in primary care practice.