Sixty percent of patients with difficult to control asthma seen in our outpatient clinic are obese. The impact of weight reduction in this subpopulation of asthmatics has not been studied. Our aim is to evaluate the impact of weight reduction on asthma control of these patients.

Study design: interventional, open label, randomized

Patients selection

Thirty-three difficult to control obese asthmatic patients, aged between 18 to 65 years old will be recruited from the outpatient clinics of the Pulmonary Division of the University of Sao Paulo Hospital.

Difficult to control asthma will be defined as patients who do not achieve asthma control (according to GINA) despite best treatment regimen and checked adherence after at least three months of treatment.

Intervention: Patients will be divided in two groups: asthma treatment plus weight loss program or asthma treatment alone for 6 months without drug dose changing.

Procedures (baseline and after 6 months) - quality of life questionnaire, asthma control questionnaire, lung function tests, serum and sputum inflammatory markers.

Inclusion Criteria:

• Difficult-to-treat asthma
• Body mass index > 30kg/m2

Exclusion Criteria:

• Subjets older than 65 years
• Current smoking
• Past smoking history (> 10 pack-year)
• Pregnancy
• Contraindication for Orlistat or Sibutramine