Participants in weight loss programs typically set unrealistically high weight loss goals that some believe are detrimental to success. This study examined outcomes associated with goal and ideal body mass index (BMI). Participants (N=1801) were enrolled in a weight loss trial comprised of low-intensity mail or telephone interventions vs usual care. Goal and ideal weight losses were assessed by asking participants how many pounds they expect to lose in the program (goal) and how much they would like to weigh (ideal). Goal and ideal weight losses were unrealistically high (men: -16 and -19%, women: -21 and -27%). For women, less realistic goals were associated with greater weight loss at 24 months. Goals were not associated with participation or weight loss for men. Results are more supportive of the idea that higher goals motivate women to lose weight than of the hypothesis that high goals undermine effort.