Inclusion Criteria:

• Loss of 10% of usual body weight, OR loss of 5% of usual body weight within the previous 6 months, OR BMI20kg/m2. If the candidate is taking a protease inhibitor, he/she must have not regained weight since initiating the medication over a period of at least 4 weeks prior to screening.
• Documented HIV-positive
• Able to eat
• English-speaking
• Compliance with medical regimens
• For heterosexually active women: willingness to use an effective means of birth control
• Patient and physician not planning to start new treatments for HIV infection or weight loss during the 12 weeks of study.

Exclusion Criteria:

• Vomiting 1 time/day or diarrhea 4 times/day on average in the previous week
• Fever 101 F within the previous week
• Receiving induction treatment for one of the following (new diagnosis or recurrence within 4 weeks):

Pneumocystis carinii pneumonia Cryptococcal meningitis Cytomegalovirus retinitis or pneumonitis Toxoplasmosis Mycobacterium avium complex Visceral Kaposi's Sarcoma Lymphoma Pulmonary tuberculosis

• Received corticosteroids, estrogens, progesterones, androgens, oral anticoagulants, or growth hormone within the previous three months
• History of life-threatening reaction to oxandrolone or testosterone
• Currently pregnant
• History of congestive heart failure, myocardial infarction, angina/coronary artery disease, uncontrolled hypertension, cerebrovascular accident, hepatic failure, bleeding disorder, diabetes, nephrotic syndrome, cancer of the breast or prostate, or hypercalcemia
• Milk product allergy
• Current use of injected drugs
• Participation in an exercise program or strength training within the previous 4 weeks
• Any medical condition which renders the participant physically incapable of performing strength exercises
• Serum total testosterone level at least 300ng/ml, unless patient and primary physician prepared to begin testosterone injections concurrent with study enrollment (men only).