To what extent is the metabolic syndrome (MetS) determined beyond its recognized components? In 1702, middle-aged men and women without MetS at baseline, MetS development was identified in 546 participants at a mean of 10.1-year follow-up. Participants subsequently developing MetS had, beyond higher values of MetS traits, significantly higher total and low-density lipoprotein cholesterol, apolipoprotein B, C-reactive protein (CRP), -glutamyl transferase (GGT), and lower high-density lipoprotein cholesterol. Females were significantly more frequent never smokers and males had lower values of total testosterone. In logistic regression analyses, adjusted for sex, age, and smoking status, MetS was predicted disparately in the sexes, whereas males exhibited, beyond abdominal obesity, CRP, GGT, and sex hormone-binding globulin (SHBG) as independent predictors, abdominal obesity was not an independent predictor in females in whom other than age, CRP conferred MetS risk, whereas SHBG was and current smoking tended to be protective. A surrogate of hepatic steatosis proved a major mediator of abdominal obesity in determining incident MetS (relative risk, 5.6 [95% confidence interval, 3.4-9.3]) in each sex. We confirm that GGT and SHBG are novel independent MetS determinants. Hepatic steatosis is the major predictor of MetS mediating adiposity in each sex. Abdominal obesity is not an independent determinant in Turkish women in whom autoimmune activation seems to prevail before MetS development.