Weight loss and muscle wasting commonly occur in patients with chronic obstructive pulmonary disease (COPD). A decreased dietary intake and elevated energy requirements underlie weight loss in these patients. Disturbances in intermediary metabolism caused by altered anabolic and catabolic mediators such as hormones, cytokines, and growth factors, and resulting in disproportionate muscle wasting have been described. Nutritional supplementation in combination with an anabolic stimulus (e.g. exercise) has been shown effective in improving functional capacity, health status, and mortality in most depleted patients. Nutritional or pharmacologic modulation of the catabolic response may further enhance the response in the near future.