Malnourished COPD patients demonstrate energy requirements significantly above predicted needs especially during activity. Recognition of this altered metabolic state is essential to the design of any nutritional intervention program. This factor alone, however, cannot explain the wasting syndrome observed in these patients. The elevated demands appear to combine with recognized factors which act to limit caloric intake. Nutritional repletion with calorie and protein supply proportional to demand is associated with weight gain, nitrogen retention, and improvement in physiologic parameters of muscle strength. Greater success of outpatient nutritional repletion in this population is dependent on alternative feeding strategies to deal with those symptoms which limit caloric intake, especially during a disease exacerbation. Future clinical research must explore these strategies before an adequate assessment of the risk and cost-benefit ratio of nutritional intervention can be determined. Additional work is indicated in techniques to identify those patients who would benefit from calorie supplementation as well as techniques to monitor the response of these individuals. Information gathered from the continued study of this population of stable outpatients with COPD will have wide application to the entire COPD patient population. This includes those patients with respiratory failure on mechanical ventilation, where numerous complicating factors makes the study of nutritional intervention and respiratory muscle function difficult.