In contrast, being underweight might make you feel weak and tired, and might make you more likely to get an infection. People with COPD use more energy while breathing than the average person. Therefore, the pulmonary (breathing) muscles in someone with COPD might require up to 10 times the calories needed by a person without COPD. It is important for you to consume enough calories to produce energy in order to prevent wasting or weakening of the diaphragm and other pulmonary muscles.