 Baseline Testing: Eligible patients will be tested at the General Clinical Research Center GCRC of Massachusetts General Hospital or at the GCRC at Massachusetts Institute of Technology MIT. For women with regular menses, the admission will correspond to the early follicular phase. Patients will receive a menstrual history calendar to submit at the baseline and 16 week visits. A complete history and physical exam will be performed, including a detailed history of all drugs being used in the treatment of the HIV disease or any associated conditions. Weight will be measured and expressed as a percentage of ideal body weight IBW and body mass index. Blood will be sampled to determine hormonal function testosterone, free testosterone, SHBG, estradiol, LH, and FSH, nutritional status albumin, prealbumin, lipid parameters HDL, LDL, cholesterol, triglycerides, immune function CD4, viral load, CBC, and thrombolytic markers t-PA, PAI-1. An HIV test will be performed at the baseline visit only, in order to document patient status. Glucose homeostasis will be measured with the use of fasting glucose and insulin levels and an oral glucose tolerance test OGTT. Heart rate will be monitored to test cardiovascular function. A spot urine will be collected for bone markers and beta-human chorionic gonadotropin bHCG. Lean body mass and fat mass will be determined by a dual energy x-ray absorptiometry DEXA to be performed at the MIT CRC; total body water will be determined by bioimpedance analysis; muscle cross-sectional area will be determined by anthropometric measurements. A quantitative computed tomography CT scan of the thigh and abdomen will be done to measure visceral and subcutaneous fat. A Magnetic Resonance Spectroscopy of calf muscles for determination of lipid concentrations in skeletal muscle will be done. Subjects with contraindications to magnetic resonance imaging MRI will be able to remain in the protocol, but the MR-Spectroscopy will not be performed. A complete dietary assessment and resting energy expenditure will be performed. Quality of life will be assessed using the MOS HIV questionnaire and an activity questionnaire as well as the Karnofsky performance assessment. 