Protein calorie malnutrition is frequently observed in patients with chronic obstructive pulmonary disease (COPD). The main mechanism is hypermetabolism essentially resulting from increased oxygen consumption of the respiratory muscles. Malnutrition is associated with poor prognosis, irrespective of age and respiratory function impairment. Malnutrition has several harmful consequences on the respiratory system: atrophy and decreased strength of the respiratory muscles, decreased exercise performance, decreased quality of life, and likely increased risk of community-acquired and nosocomial pneumonia. A long-duration oral supplementation may improve the nutritional status and exercise tolerance in ambulatory COPD patients. The interest of anabolic drugs, especially recombinant growth hormone, has not been demonstrated in malnourished COPD patients.