Effectiveness of contingency contracting: component of a worksite weight loss program

The purpose of this study was to measure weight loss in overweight employees of a large corporation in Western Michigan who all received the same education on how to lose weight, but were randomly assigned to one of three groups: contingency contracting with a partner, contingency contracting alone, or no contingency contracting. A pretest-posttest quasi-experimental design was used and data were collected by a demographic questionnaire and measure of weight at the initial, 10th, and 23rd weeks. A total of 84 subjects completed the 10 week weight loss program and 57 subjects returned for the 23rd week follow up weight. Each group lost a significant amount of weight from pre-program to 10 weeks; however, there were no significant differences across groups. Although the groups were not significantly different from each other, the results support the value of individualizing interventions and offer insight into how demographic variables may affect attrition and methods chosen for weight loss.