It is unclear whether regular exercise alone (without calorie restriction) is a useful strategy to reduce adiposity and obesity-related metabolic risk factors in obese girls. We examined the effects of aerobic (AE) versus resistance exercise (RE) alone on visceral adipose tissue (VAT), intrahepatic lipid and insulin sensitivity in obese girls. Forty-four obese adolescent girls (BMI >95^th, 12-18 yrs) were randomized to 3-months of 180 min/week AE (n=16) or RE (n=16) or a non-exercising control group (n=12). Total fat and VAT were assessed by MRI and intrahepatic lipid by proton magnetic resonance spectroscopy. Intermuscular AT (IMAT) was measured by CT. Insulin sensitivity was evaluated by a 3-hour hyperinsulinemic (80 mU/m²/min)-euglycemic clamp. Compared with controls (0.13 ± 1.10 kg), Body weight did not change (P>0.1) in the AE (-1.31 ± 1.43 kg) and RE (-0.31 ± 1.38 kg) groups. Despite the absence of weight loss, total body fat (%) and IMAT decreased (P<0.05) in both exercise groups compared with control. Compared with control, significant (P<0.05) reductions in VAT ( -15.68 ± 7.64 cm²) and intrahepatic lipid ( -1.70 ± 0.74%), and improvement in insulin sensitivity ( 0.92 ± 0.27 mg/kg/min per µU/ml) were observed in the AE group, but not the RE group. Improvements in insulin sensitivity in the AE group were associated with the reductions in total AT mass (r = -0.65, P=0.02). In obese adolescent girls, aerobic exercise, but not resistance exercise is effective in reducing liver fat, visceral adiposity and improving insulin sensitivity independent of weight loss or calorie restriction.