Methods: The prevalence of AHR and confirmed asthma (international clinical and functional definition) are determined based on pulmonary function test (spirometry, volume determinations, arterial blood gas, measurement of the resistance of the respiratory system with evaluation of the response to deep inhalation, methacholine challenge, exhaled NO measurement, nocturnal polygraphy and oeso-gastroscopy) results obtained from 150 obese (BMI > 35). The FDI and CVTV will be determined based on the tidal volume obtained from thoracic and abdominal plethysmography inductance measurements during the polygraphy. A nocturnal polygraphy is systematically done in these women to search for a Sleep Apnea Syndrome. 30 healthy (non asthmatic, normal exhaled NO value, BMI 18.5 to 25) women will constitute a control group. The size of the groups have been calculated based on literature data concerning the FDI and CVTV.