The purpose of this trial is to study the effect of megestrol acetate in the gain of body weight in patients with severe Chronic obstructive pulmonary disease in order to improve the survival of the patients.

It has been demonstrated that the body weight measured as a Body mass index (BMI)is an independent risk factor of mortality in the severe COPD.It seems to be one influence of inflammatory factors in the development of denutrition in these patients.

The use of especial diets has no so good results in the aim to improve the weight, being necessary to complement with muscular rehabilitation or anabolic products. The megestrol acetate has demonstrated good results in a short period of time, nevertheless the studies are scarce.

The beneficial effects of the megestrol acetate seems to be mediated by cytokines.

Inclusion Criteria:

• Clinical diagnose of COPD (criteria ATS/ERS 2004)
• Clinical stability more than 3 months
• Smokers or ex-smokers of more than > 10 boxes/year than do not modify their smoking habit during the study.
• FEV1 (post-bronchodilator) < 50%. FEV1/FVC ≤ 70
• Negative answer to bronchodilator(≤ 20% del FEV1 o ≤ 200 ml.after 400 mcg.de salbutamol inhaled)
• BMI < 21 Kg/m2 ó BMI 21-25 Kg/m with loss weight of 5% of the habitual body weight in the last 3 months, without other reason that could explain it independently of the COPD.

Exclusion Criteria:

• Use of nasogastric catheter
• Concomitant treatment with steroid, anabolics or other progestagens.
• Loss of body weight related with other causes: hyperthyroidism, enteral malnutrition ( Crohn disease...), neoplasias,etc
• Treatment with Megestrol Acetate in the last 6 months