The numerous aspects of provider behavior and program content and process that may influence both the enrollment of clients (i.e., which kinds are attracted to the program) and the outcomes of treatment have not been well studied (Blackburn, 1993; Wadden, 1993). However, some program variables are consistently related to outcomes. Length of treatment predicts weight loss. This is shown, for example, in a study where increasing the treatment length from 20 to 40 weeks increased weight loss from 10.5 kg at week 20 to 13.5 kg at week 40 (Perri et al., 1989). Social influences from therapist contact and peer support may be partly responsible for this result, apart from the effect of the client's receiving extended training in behavioral self-management methods. Control over eating and exercise may be improved when individuals rely on peers to get them through situations involving temptations (Goodrick and Foreyt, 1991). Using peer-influence processes such as group problem solving and telephone contacts improves long-term weight management (Perri et al., 1992).
Studies investigating the effect of exercise on weight loss have reported mixed results (Wadden and Letizia, 1992). However, exercise has been shown to be one of the best predictors of maintenance, so it makes sense to emphasize its importance during treatment and follow-up. Exercise may improve body composition and blood lipid profiles (Blair, 1993a; Uchino et al., 1991) as well as reduce stress and improve well-being. These health factors should be further researched and promoted for successful weight management.
Self-monitoring (i.e., the recording of dietary intake and exercise) is the cornerstone of behavioral treatment and has been correlated with success (Perrri et al., 1989). While the information feedback from this process appears to be highly useful in treatment, it is difficult to determine whether self-monitoring is a cause or correlate of good results.
Goal setting in terms of eating, exercise, and weight goals has also been correlated with success at weight loss (Bandura and Simon, 1977; Dubbert and Wilson, 1938). This activity goes together with the concept of making gradual, incremental changes to ensure success. Slowing the rate of eating is also correlated with successful weight management (Speigel et al., 1991).
Maintenance of reduced weight is the most difficult aspect of long-term treatment. Interventions that provide clients with a "maintenance" program produce better maintenance of weight loss than those without a