Unlike calorie restriction (CR), exercise fails to extend maximum lifespan, but the mechanisms that explain this disparate effect are unknown. We used a 24-week protocol of treadmill running, weight matching and pair feeding to compare the effects of exercise (EX) and CR on biomarkers related to aging. This study consisted of young controls, an ad libitum-fed sedentary group, two groups that were weight matched by EX or 9% CR, and two groups that were weight matched by 9% CR+EX or 18% CR. After 24 weeks, ad libitum-fed sedentary mice were the heaviest and fattest. When comparing weight-matched groups, mice that exercised were leaner than CR mice. Ad libitum-fed EX mice tended to have lower serum IGF-1 than fully-fed controls, but no difference in fasting insulin. Mice that underwent 9% CR or 9% CR+EX, had lower insulin levels; the lowest concentrations of serum insulin and IGF-1 were observed in 18% CR mice. EX resulted in elevated levels of tissue heat shock proteins, but did not accelerate the accumulation of DNA damage. Thus, failure of exercise to slow aging in previous studies is not likely the result of increased accrual of oxidative damage, and may instead be due to an inability to fully mimic the hormonal and/or metabolic response to CR.