Aerobic exercise but not resistance exercise reduces intrahepatic lipid content and visceral fat and improves insulin sensitivity in obese adolescent girls: a randomized controlled trial.
Level 2 - randomized trial
Individual randomized controlled trial
PubMed 24045865 · doi:10.1152/ajpendo.00285.2013
What was done
Forty-four obese adolescent girls (BMI ≥95th percentile, aged 12-18 years, waist circumference 106.5 ± 11.1 cm) were randomized to 3 months of 180 min/week aerobic exercise (AE, n = 16), resistance exercise (RE, n = 16), or a non-exercising control group (n = 12), without caloric restriction. Total body fat and visceral adipose tissue (VAT) were measured by MRI, intrahepatic lipid content by proton magnetic resonance spectroscopy, intermuscular adipose tissue (IMAT) by CT, and insulin sensitivity by a 3-hour hyperinsulinemic-euglycemic clamp (80 mU·m⁻²·min⁻¹).
What was found
Body weight did not change significantly (P > 0.1) in controls (0.13 ± 1.10 kg), AE (-1.31 ± 1.43 kg), or RE (-0.31 ± 1.38 kg). Despite the absence of weight loss, total body fat percentage and IMAT decreased significantly (P < 0.05) in both exercise groups relative to control. Compared with control, significant (P < 0.05) reductions in VAT (Δ-15.68 ± 7.64 cm²) and intrahepatic lipid (Δ-1.70 ± 0.74%), along with improved insulin sensitivity (Δ0.92 ± 0.27 mg·kg⁻¹·min⁻¹ per μU/ml), occurred only in the AE group. Improvements in insulin sensitivity in the AE group correlated with total adipose tissue reduction (r = -0.65, P = 0.02). Resistance exercise produced no significant change in VAT, liver fat, or insulin sensitivity compared to control.
Why it matters
Aerobic exercise can reduce visceral and intrahepatic fat and enhance insulin sensitivity in obese adolescents independently of weight loss or caloric restriction, whereas resistance exercise at equal weekly volume does not confer these specific liver and visceral fat benefits.
Limits
The sample size was small (n = 44 across three arms) and the intervention duration was relatively short (3 months). The study included only obese adolescent girls, limiting generalizability to males or other age groups, and long-term sustainability was not evaluated.
Cited by
- contradicts Minute-for-minute over short durations such as 30 minutes per day, strength training leads to greater improvements in insulin sensitivity than aerobic training.