Weight gain after lung reduction surgery is related to improved lung function and ventilatory efficiency.

Rationale: Lung volume reduction surgery (LVRS) is associated with weight gain in some patients, but the group that gains weight after LVRS and the mechanisms underlying this phenomenon have not been well characterized.

Objectives: To describe the weight change profiles of LVRS patients enrolled in the National Emphysema Treatment Trial (NETT) and to correlate alterations in lung physiological parameters with changes in weight.

Methods: We divided 1,077 non-high-risk patients in the NETT into groups according to baseline body mass index (BMI): underweight (<21 kg/m(2)), normal weight (21-25 kg/m(2)), overweight (25-30 kg/m(2)), and obese (>30 kg/m(2)).