Waist circumference is associated with pulmonary function in normal-weight, overweight, and obese subjects

Background: Obesity is becoming a serious public health issue and is related to lung dysfunction. Because both weight and height are indicators of body size, body mass index (BMI) may not be an ideal index of obesity in prediction of pulmonary dysfunction. Objective: The objective of the study was to determine the predictability of waist circumference (WC) and BMI for pulmonary function in adults with and without excess body weight. Design: A cross-sectional study of 1674 adults aged >= 18 y was conducted in a rural community. Height, weight, WC, and pulmonary function were measured. Multivariate analysis was conducted. Results: WC was negatively associated with forced vital capacity and forced expiratory volume in 1 s, and the associations were consistent across sex, age, and BMI categories. On average, a 1 -cm increase in WC was associated with a 13-mL reduction in forced vital capacity and an 11-mL reduction in forced expiratory volume in 1 s. The association between WC and pulmonary function was consistent in subjects with normal weight, overweight, and obesity. In subjects with normal weight, BMI was positively associated with forced vital capacity and forced expiratory volume in 1 s. Conclusion: WC, but not BMI, is negatively and consistently associated with pulmonary function in normal-weight, overweight, and obese subjects.