Monkeys were randomized into study groups for a cross over design evaluating the acute effects of 3 different monkey diets: standard NIH chow, the NIA 1-87 diet, and the Wisconsin Harlan Teklad diet. The latter two diets are used at the respective sites for long-term studies of calorie restriction effects on function, morbidity, and mortality. For baseline and each 3-month timepoint, the following measures were collected: body weight, morphometric measures, body composition scan, pulse wave velocity for arterial stiffness, glucose tolerance test, biopsy of liver, fat and muscle, and banked serum and plasma samples. All data collection was completed this year and samples are currently being analyzed.