Effects of Intervention Characteristics on Willingness to Initiate a Weight Gain Prevention Program

Purpose: To determine characteristics of weight gain prevention programs that facilitate engagement. Design: Randomized factorial experiment (5 × 2). Setting: Recruited nationally online. Participants: Adults aged 18 to 75 with body mass index ≥25 who decline a behavioral weight loss intervention (n = 498). Measures: Participants were randomly presented with one of 10 possible descriptions of hypothetical, free weight gain prevention programs that were all low dose and technology-based but differed in regard to 5 behavior change targets (self-weighing only; diet only; physical activity only; combined diet, physical activity, and self-weighing; or choice between diet, physical activity, and self-weighing targets) crossed with 2 financial incentive conditions (presence or absence of incentives for self-monitoring). Participants reported willingness to join the programs, perceived program effectiveness, and reasons for declining enrollment. Analysis: Logistic regression and linear regression to test effects of program characteristics offered on willingness to initiate programs and programs’ perceived effectiveness, respectively. Content analyses for open-ended text responses. Results: Participants offered the self-weighing-only programs were more willing to initiate than those offered the programs targeting all 3 behaviors combined (50% vs 36%; odds ratio [OR] = 1.79; 95% confidence interval [CI], 1.01-3.13). Participants offered the programs with financial incentives were more willing to initiate (50% vs 33%; OR = 2.08; 95% CI, 1.44-2.99) and anticipated greater intervention effectiveness (β =.34, P =.02) than those offered no financial incentives. Reasons for declining to initiate included specific program features, behavior targets, social aspects, and benefits. Conclusion: Targeting self-weighing and providing financial incentives for self-monitoring may result in greater uptake of weight gain prevention programs. Study Preregistration: https://osf.io/b9zfh, June 19, 2018.