One thousand three-hundred and eighty-nine obese outpatients were followed by 28 practitioners. They were enrolled in a multidisciplinary weight control program for at least 1 year. The major components of the program include a commercial very low calorie diet (Pro'gram18 VLCD), behavior modification, and exercise. There was a significant decrease in body weight compared with baseline of approximately 12.3+/-5.3 kg at the end of the maintenance period; the weight loss was achieved essentially at the expense of fatty mass, -10.3+/-5.5 kg at 90 days while fat-free mass loss was -2.0+/-2.5 kg at 90 days. Mean serum total cholesterol and triglycerides were also lowered and systolic and diastolic blood pressure and fasting blood glucose values were normalized at the end of the weight-loss phase. Obese outpatients lost substantial amounts of weight using VLCD, reduced the risk factors associated with obesity, and had encouraging long-term results, with weight loss maintained at 2-year follow-up.