ABSTRACT Much of the worldwide population is obese or overweight. However, the effects of body fat on a personâs workplace success, especially in the long term, are not well known. Further, we have little insight on the dominant mechanisms by which body fat influences career outcomes. Aiming to understand if, how, and when employee body fat impacts career success over time, we challenge prior theory (i.e. stigma theory) and employ a novel medical perspective to suggest that an employeeâs health â in the form of illnesses like cardiovascular disease and diabetes â determines the relationship between employee body fat levels and long-term work success. Furthermore, we integrate research from evolutionary biology to consider the moderating role of employee sex in the health process and probe effects by industry. Longitudinal results from a nationally representative, multi-wave sample (across 20 years) show that employee health â but not stigmatization or other explanations â mediates the negative relationship between employee body fat levels and career success. Moreover, findings reveal that employee sex does not moderate this indirect effect, indicating that high body fat men and women equally experience adverse career effects due to the serious medical impairments they incur. Industry further qualifies these effects.