Obesity and overweight have reached near-epidemic proportions in the United States. There is a need to further investigate intervention strategies designed to help individuals manage their weight by improving diet and exercise behaviors. We designed a multidisciplinary weight management program that included healthy eating, regular exercise, and behavioral changes based on the Transtheoretical Model. The program focused on a healthy lifestyle rather than weight loss. Overweight and obese adults (n = 144; BMI = 32.5 +/- 3.8) participated in a 6-month clinic-based weight management program. The first 3 months of the program were intense (twice weekly for 2 h) followed by 3 months of reduced clinical contact. Assessments completed at baseline, 3 months, and 6 months included weight, body composition, BMI, total cholesterol, HDL-C, LDL-C, and 24-h diet recalls. VO(2max) was assessed at baseline and at 3 months. Subjects experienced significant decreases in weight, percentage body fat, BMI, total cholesterol, LDL-C, total caloric intake, and the percentage of energy intake from dietary fat as well as a significant increase in VO(2max) (P < 0.05) at 3 months. Changes were maintained at 6 months, with weight, total cholesterol, and LDL-C demonstrating further improvement. A clinic-based weight management program that focuses on lifestyle is successful at promoting changes in exercise and dietary behaviors. These changes appear to promote good health, as evidenced by moderate weight loss, increased cardiorespiratory fitness, and improved lipid profiles.