The impact of oral nutritional supplementation during an acute exacerbation of COPD on functional status was assessed through measuring change in lung function, strength testing, and general well-being. Subjects hospitalized for an acute exacerbation of COPD (n = 33) were randomized to extra nutritional support or the regular hospital care. They consumed an additional 10 kcal/kg/d. Outcome measures were measured at 2 wk as change scores. Forced vital capacity (% predicted) improved in the treatment group as compared with the control group (+8.7% versus -3.5%, p = 0.015), and change in FEV1 was in the same direction but not significantly different (p = 0.099). There were no changes in handgrip strength or respiratory muscle strength, but there was a trend towards more improvement in the general well-being score (+11.96 versus -10.25, p = 0.066). Almost all subjects were in negative nitrogen balance, indicating muscle wasting. The degree of muscle wasting was strongly correlated with the dose of corticosteroids (r = 0.73, p < 0.005). In conclusion, it is difficult to prevent important muscle wasting in patients with COPD treated with corticosteroids, but some small gains were observed with increased dietary intake.