Introduction Employee wellness programs show mixed effectiveness results. This study examined the impact of an insurer's lifestyle modification program on healthcare costs of obese individuals. Methods This nonrandomized comparative effectiveness study evaluated changes in healthcare costs for participants in two incentivized programs, an Internet-mediated pedometer-based walking program (WalkingSpree, n=7,594) and an in-person weight-loss program (Weight Watchers, n=5,764). The primary outcome was the change in total healthcare costs from the baseline year to the year after program participation. Data were collected from 2009 to 2011 and the analysis was done in 2014-2015. Results After 1 year, unadjusted mean costs decreased in both programs, with larger decreases for Weight Watchers participants than WalkingSpree participants (-$1,055.39 vs -$577.10, p=0.019). This difference was driven by higher rates of women in Weight Watchers, higher baseline total costs among women, and a greater decrease in costs for women in Weight Watchers (-$1,037.60 vs -$388.50, p=0.014). After adjustment for baseline costs, there were no differences by program or gender. Conclusions Comparable cost reductions in both programs suggest that employers may want to offer more than one choice of incentivized wellness program with monitoring to meet the diverse needs of employees.