Male C57BL/6J mice were purchased from The Jackson Laboratory (JAX) through the Diet-Induced Obese Mouse service, which assigns animals to one of two irradiated, purified open-source diets (Research Diets Inc.) beginning at 6 weeks of age: 1) control-fat diet (CF) containing 10% kcal fat (D12450Bi), or 2) high-fat diet (HF) containing 60% kcal fat (D12492i). 3 animals assigned to the exercise cohort in each diet and one HF-sedentary animal died during the course of the experiment due to undetermined causes, resulting in the following final group sizes: CF-sedentary (n=12), CF-exercise (n=9), HF-sedentary (n=13), HF-exercise (n=9). Abbreviations: OMRF (Oklahoma Medical Research Foundation), DEXA (dual X-ray absorptiometry system), GTT (glucose tolerance testing), and MRI (magnetic resonance imaging).