Postural changes are known to affect normal lung volumes. A reduction in sitting to supine functional residual capacity (FRC) is well-described in non-obese subjects adopting a supine position. However, postural changes in lung volumes in the obese require further exploration. We aimed to longitudinally address the effects of weight loss on postural changes in lung volumes and pulmonary function, in obesity. We tested the hypothesis that supine reduction in FRC would be absent in morbid obesity and recovered upon weight loss.

Inclusion Criteria:

• subjects scheduled for bariatric surgery (BMI over or equal to 40 kg/m2)

Exclusion Criteria:

• Subjects with respiratory and cardiac history (asthma, COPD, heart failure) were excluded.

Twelve morbidly obese adults (BMI over or equal to 40 kg/m2) scheduled for bariatric surgery at the Montpellier university hospital were recruited. They were 3 men and 9 women.