Stimulating Weight Stigma in Future Experimental Designs on Physical Activity - Development and Pilot Validation of a Video Instrument.

Objective: There is a need for more experimental research on weight stigma and physical activity, specifically among men with obesity. Yet, validated procedures are required. The goal of this study was i) to develop a 10-min video instrument for the experimental induction of physical activity-related weight stigma (including a neutral control video), and ii) to collect information with regards to its content, face, construct, and criterion validity.

Methods: To ensure content and face validity, two experts gave repeated feedback on the video development. In addition, two novices reviewed the video. Subsequently, we conducted a separate experiment: 60 adult men (18-52 years, 31 with overweight, 29 with normal weight) were randomly assigned to one of the two video conditions, stratified by BMI.

Results: After the treatment, the stigma group showed higher scores of negative affect and attitudes against obesity (convergent validity). As expected, there were no differences in measures of depression and general stress (discriminant validity). The BMI of the participants in the stigma group correlated positively with some indicators of negative affect (criterion validity).

Conclusion: Our study provides preliminary evidence for the validity of the video tool. Therefore, it can be used in future trials to investigate the effects of weight stigma on physical activity behavior.