Abdominal obesity (AO) is associated with endothelial dysfunction, inflammation, insulin resistance, diabetes mellitus, hypercholesterolemia, metabolic syndrome, and cancer. AO is a multifactorial disorder arising from genetic, environmental, socioeconomic, and behavioral factors. Thus, in this chapter, we devote ourselves to the exercise of trying to explain the epidemiology of AO in adults. We showed the increasing prevalence of AO around the world, and a gender difference in this determination was observed. Among women, the population group who is the most affected by AO, a higher prevalence of AO is observed in individuals living in low-or middle-income countries (LMIC), who are older, multiparous, and in the menopausal transition, and who belong to the poorest strata and have lower educational level. While among men, the risk of AO is positively associated with socioeconomic status, particularly in LMIC. Regarding behavioral factors (eating frequency, sleep duration, physical activity, and smoking), gender differences are difficult to be detected due to the lack of studies investigating their association with AO according to sex. However, the current evidence suggests that men benefit more from consuming a greater number of meals a day and women are more affected by the harmful effects of physical inactivity. We argued AO, despite biological conditions associated with behavior factors, should be examined as an important issue of gender inequality in health, possibly mediated by socioeconomic and behavioral differences between men and women.