Obstructive sleep apnea/hypopnea (OSAH) is a common chronic disease that is associated with daytime sleepiness, impaired health-related quality of life (QOL), and increased risk of hypertension and cardiovascular disease. The most common treatment is continuous positive airway pressure (CPAP), although adherence to CPAP is poor in more than one-third of patients. Weight loss can clearly lessen the severity of OSAH, but although short-term dietary weight loss can often be achieved it is difficult to maintain. Regular aerobic exercise is associated with a lower prevalence of OSAH in observational studies after adjustment for body habitus, and in two small clinical trials moderate exercise was associated with a substantial decrease in OSAH severity despite little or no weight loss. Demonstrating that dietary weight loss and moderate physical activity, promoted in the home setting, independently improve OSAH severity will have a major impact on the therapeutic approach to OSAH, a disease that is highly prevalent in the VA population.