Inclusion Criteria:

- Ages 55-75 years at first group meeting

- Physically able to undertake a moderate exercise program

- Sedentary activity pattern (exercising < 2 times/week for 20 minutes at a level to
produce sweating)

- Postmenopausal (not experiencing menstrual periods for the previous 12 months or FSH
>30 mIU/ml; for women who have had a hysterectomy, an FHS >30 mIU/ml will classify
them as postmenopausal)

- Body Mass Index (BMI) greater than 25.0

- Able to follow directions and fill out questionnaires, and exercise diaries and logs
in English

- Agrees to be randomly assigned to either the exercise intervention or control group

- Gives informed consent to participate in all screening and study activities

- Able to come to the FHCRC for clinic visits and classes, to the UW Medical Center for
CT scans, and to the UW NETT for measurements and instruction

Exclusion Criteria:

- Plans to leave Western Washington within the follow-up period

- Using hormone replacement, tamoxifen, or oral contraceptives in past 6 months

- Currently having severe hot flashes (that might prompt participant to start hormone
replacement therapy before the end of study)

- Current unstable thyroid disease or unstable dose of thyroid medications or TSH >5.0
IU/ml or <0.5 IU/ml

- Invasive cancer in the past 10 years (except nonmelanotic skin cancer)

- Any other endocrinologic abnormality

- Breast, endometrial, ovarian, or melanoma cancer or carcinoma-in-situ at any time

- Morbidly obese (BMI > 40)

- Current or planned use of corticosteroids

- Currently on or planning to enter a structured weight loss program or to take diet
drugs

- Current use of certain other medications, such as any likely to interfere with
adherence to an exercise program or likely to interfere with study outcomes

- Moderate to high alcohol intake (more than 2 drinks per day)

- Current smoker

- Diabetes mellitus (fasting hyperglycemia)

- Abnormal screening labs (hematocrit < 32 or > 48, white blood cells < 3.0 or > 15.0,
potassium < 3.5 or > 5.0, fasting glucose > 140, creatinine > 2.0), or abnormalities
on screening physical judged by study physicians to contraindicate participation in
an exercise program

- Contraindications for entry into a training program118 including: unstable angina,
uncontrolled hypertension (systolic > 200, diastolic > 100), orthostatic hypotension
(> 20), moderate/severe aortic stenosis, uncontrolled arrhythmia, uncontrolled
congestive heart failure, third degree heart block, pericarditis, myocarditis,
pulmonary/systemic embolism within the past 6 months, thrombophlebitis, ST
displacement > 3 mm at rest, history of cardiac arrest)

- Contraindications for exercise testing118 including: recent (within 6 months) cardiac
event (MI, pulmonary edema, myocarditis, pericarditis), unstable angina, uncontrolled
arrhythmia, third degree heart block, left bundle branch block, acute congestive
failure, recent (within 6 months) pulmonary/systemic embolus, severe electrolyte
abnormality

- Meets criteria to stop screening exercise test118 as decided by overseeing physician
(Dr. Schwartz or McTiernan)

- volunteering in order to lose weight

- alcohol or drug abuse, significant mental illness (as assessed by study staff
impression)