Hypothesis 3: A decrease in markers of oxidative stress to lipid (urinary isoprostanes) DNA (strand breaks) in blood and protein (carbonylation and thiol oxidation) in blood and skeletal muscle tissue after 1 and 2 years of CR will be observed. Aim 3: Determine the changes in oxidative stress after 1 and 2 years of 25% CR by measuring urinary isoprostanes, serum carbonyls, DNA damage in nucleated blood cells and protein oxidation (carbonyls and oxidation of cysteine residues) in skeletal muscle.