Twelve weeks of high- or moderate-intensity interval training in obese adolescent females is associated with reductions in fasting insulin and HOMA-IR, with a greater reduction in HOMA-IR observed in the high-intensity group (-28.7%) compared to the moderate-intensity group (-22.6%).

When obese adolescent females do high- or moderate-intensity interval training, their fat cells shrink because they burn more energy. Smaller fat cells release less leptin and reduce inflammation, which lets insulin work better. Muscles respond by moving more glucose transporters to their surface, pulling glucose out of the blood. This lowers blood sugar, so the pancreas doesn't need to make as much insulin. The more intense training causes greater fat loss and muscle adaptation, leading to a bigger drop in insulin levels.