The effect of contract witnessing on motivation and weight loss in a weight control program

To investigate the impact which commitment has on the achievement of behavioral-change goals in a weight control program, a behavioral contracting process was used. One-hundred six adult volunteers were randomly identified as treatment or control group members and co-participated in a four-week, eight-hour, behavioral self-management weight control program. As part of homework assignments, all participants were provided with three take-home contracts which were to be returned either signed by the participant only (control group with baseline commitment) or by the participant and at least one friend, relative, or peer (treatment group with enhanced commitment). Analyses of comparable treatment and control group members shows the treatment group holding significantly stronger behavioral intentions 10 to 15 weeks after the program ended and losing weight at a significantly faster rate. Implications for program planning, implementation, and evaluation are discussed.