Body composition analysis and changes in airways function in obese adults after hypocaloric diet.

STUDY OBJECTIVES To determine the relationship between weight-loss and pulmonary function indexes, focusing on forced expiratory flows (ie, FEV(1), forced expiratory flow at 50% of vital capacity [FEF(50)], forced expiratory flow at 75% of vital capacity, and forced expiratory flow at 25 to 75% of vital capacity [FEF(25--75)]). Specifically, to determine the effect of losses in total and segmental fat mass (FM) and of modifications in lean body mass, after restricted hypocaloric diet, on pulmonary function among obese adults. DESIGN Cross-sectional, observational. SETTINGS Human Physiology Division, Faculty of Medicine and Surgery, "Tor Vergata" University, Rome, Italy. PATIENTS Thirty obese adults (mean [+/- SD] baseline body mass index [BMI], 32.25 +/- 3.99 kg/m(2)), without significant obstructive airway disease, were selected from among participants in a weight-loss program. MEASUREMENTS AND RESULTS Anthropometric, body composition (BC), and respiratory parameters of all participants were measured before and after weight loss. Total and segmental lean body and FM were obtained by dual-energy x-ray absorptiometry. Dynamic spirometric tests and maximum voluntary ventilation (MVV) were performed. The BC parameters (ie, body weight [BW], BMI, the sum skinfold thicknesses, thoracic inhalation circumference, thoracic expiration circumference, total FM, and trunk FM [FMtrunk]) were significantly decreased (p < or = .0001) after a hypocaloric diet. The mean vital capacity, FEV(1), FEF(50), FEF(25-75), expiratory reserve volume, and MVV significantly increased (p < or = 0.05) with weight loss. The correlation coefficient for Delta FEF(25--75) (r = 0.20) was numerically higher than Delta FEF(50) and Delta FEV(1) (r = 0.14 and r = 0.08, respectively) for the BW loss. Moreover, the correlation coefficient for Delta FEF(25--75) (r = 0.45) was significantly higher (p < or = 0.02) than those for Delta FEF(50) and Delta FEV(1) (r = 0.38 and r = 0.15, respectively) for FMtrunk loss. CONCLUSIONS This study shows that a decrease in total and upper body fat obtained by restricted diet was not accompanied by a decrease in ventilatory muscle mass. FMtrunk loss was found to have improved airflow limitation, which can be correlated to peripheral airways function.