Across three studies, we explore the workplace implications of “obesity proximity effects,” where a proximal person working with an obese individual suffers the same negative perceptions and outcomes as the obese individual. Specifically, we investigate why working with an obese coworker would affect a proximal employee’s job performance. We use this context to propose new theory-driven mechanisms to challenge the understanding of stigma-by-association processes more broadly. Studies 1–2 extend theory on stigma-by-association effects by introducing a novel self-stigmatization perspective. Results from two time-lagged, multisource field studies reveal that obesity proximity effects emerge most consistently from the proximal employee taking on the emotions associated with obese people when working with an obese coworker. Study 3 dives deeper into this self-stigmatization path through a between-person, experimental coworker simulation. Results again show that a proximal employee, when working with an obese coworker, will take on emotions associated with people who are obese, independently of their own obesity status. These studies show it is important to study the broader impact of obesity, exploring its influence on other organizational members. Implications for the obesity literature, stigma theory, and other stigmatized characteristics are discussed.