This longitudinal, controlled clinical study was conducted to compare the effects of resistance exercise (RE) and aerobic exercise (AE) on body mass index (BMI), weight, fat mass (FM), serum lipid profile, and insulin resistance in obese women who cannot adhere to energy-restricted diets. A total of 60 obese women with severe eating disorders were evaluated. Patients were randomly divided into 3 groups: control group with no exercise (n=20), group 1 with AE (n=20), and group 2 with RE (n=20). Demographic and anthropometric measurements were taken. Serum lipid fractions and fasting (FGlc) and postprandial glucose insulin (PGlc) levels were measured. Insulin resistance was calculated with use of homeostasis model assessment (HOMA-IR). Total body FM was measured by bioelectric impedance analysis. After 12 wk of exercise, significant decreases in BMI, waist and weight measurements, and FGlc, PGlc, triglyceride, and total cholesterol levels were noted in each of the study groups. Reduced low-density lipoprotein cholesterol level and FM and HOMA-IR measurements were observed only in group 1 (with AE). This study indicated that AE and RE training induces improvement in body fat composition and has a favorable metabolic effect in obese women with severe eating disorders.