This study evaluated the overall effectiveness of the Navy's three-tiered obesity treatment program and compared effectiveness across the three treatment levels. Height, weight, and body circumference measurements were obtained from 369 program participants at baseline and follow-up (6 weeks, 6 months, 12 months). Results demonstrated a significant and sustained reduction in percent body fat in all three program tiers, but the absolute losses at the end of 12 months were small: -3.7% fat for men, -4.5% fat for women. The level III tier, which employs a multidimensional approach to treatment, was the most effective program, even after differences in enrollees' initial percent body fat were taken into account. Changes in the approach to treatment and development of a supportive, long-term, behaviorally based aftercare program are recommended.