This study is one of three CALERIE trials that test the hypothesis that a reduced calorie, nutritionally sound diet increases the length of life and prevents some age-related chronic diseases such as cancer, diabetes, and cardiovascular disease. The three sites that are participating in the CALERIE trial represent a diversity of subject populations and interventional strategies.

Animal studies suggest that caloric restriction (CR), or consuming fewer calories, increases life span, and also protects against some aging-related disease processes such as artherosclerosis and type II diabetes. However, it appears that simply burning more calories through physical activity does not increase life span by itself. It is not known how CR affects humans, but based on this evidence it appears that the reduced total intake and metabolism of food is the main factor, rather than increased exercise alone.

To test this, volunteers will be placed on a program of either 20% caloric restriction or 20% increase of energy expenditure by exercise, or in a control group to be instructed in healthy living. All will be evaluated on a number of potential markers of aging, on body composition, and on risk factors for artherosclerosis and diabetes.

Participation in the study will last for 12 months. The Diet group will receive individual instruction from a registered dietician. The Exercise group will be given an individualized exercise program created by a personal trainer. The Healthy Lifestyle group will be given information on how to make healthier choices; both diet and activity will be discussed. All participants will be measured every two weeks, and will keep daily food and activity logs. All will be seen by a physician and will have lab tests done before beginning the study, at 1 month, and then 3 month intervals.

Inclusion Criteria:

• Age 50 to 60
• Women must be post-menopausal
• Normal weight to moderately overweight, (Body Mass Index [BMI] between 23 - 30)
• In good health, free of major chronic diseases or conditions
• Well motivated
• Reliable

Exclusion Criteria:

• Major chronic disease or condition that would interfere with exercise or caloric restriction (such as diabetes, coronary artery disease, significant obstructive airway disease, stroke, resting blood pressure over 170 mmHg systolic and/or 100 mmHg diastolic, history or evidence of malignancy, orthopedic or musculoskeletal problems)
• Hormone replacement therapy (DHEA, estrogen, thyroid, testosterone)
• Regular exercise twice or more per week
• Smoking
• Alcoholism
• Frequent travel