Purpose The study examined the effects of a 12-week high intensity circuit training (HICT) on abdominal fat, physical fitness, blood lipids, and insulin resistance in middle-aged obese women. Methods Thirty obese women, aged 32-48 yrs, were recruited and randomly assigned to either HICT group (TR; n = 15) or control group (CON; n = 15). Subjects in the TR group participated in HICT of which resistance exercise and aerobic exercise were performed with a duration of 40 min/session and 3 sessions/wk for 12 weeks, whereas subjects in the CON group were asked to maintain their normal life patterns. Dependent variables included abdominal fat area, body composition, physical fitness, blood lipids profiles, and insulin resistance index. Analysis of variance with repeated measures with Bonferroni corrections was used to compare the outcomes between two groups. Results Main findings of the present study were as follows: 1) compared to the CON group, the TR group had significant reductions in overall (i.e., body mass index and percent body fat) and abdominal obesity (i.e., waist circumference, total abdominal fat area, visceral fat area, subcutaneous fat area, and visceral fat area-subcutaneous fat area ratio), 2) compared to the CON group, the TR group had significant improvements in health-related physical fitness (i.e., muscular strength, muscular endurance, muscle power, flexibility, balance, and cardiorespiratory endurance), and 3) compared to the CON group, the TR group had significant improvements in fasting lipids, glucose, insulin, and insulin resistance. Conclusions The current findings of the study suggested that HICT would be an effective exercise intervention to improve metabolic complications associated with obesity and poor physical fitness in obese middle-aged women.