Background: Why is bodyweight not a predictor of lung function, while height, sex,
race, and age are predictors of lung capacity and function? In this study, we want to investigate the
association between body composition and pulmonary function. And, as much as possible, answer
the question of why bodyweight is not predictive of lung function.
Methods: This cross-sectional study was performed among 2967 employees of Tehran University
of Medical Sciences (TUMS) who participated in the TUMS Employees Cohort (TEC) study. The
body composition of the participants was measured using the Bioelectrical Impedance Analysis (BIA)
method. Anthropometric variables were also measured as a confounder. The pulmonary function
of participants was assessed by a forced spirometry test.
Results: The correlation of BIA values including fat-free mass and total body water with a pulmonary
function such as FEV1, FVC, and FEF25-75 is higher than most anthropometric values such as
weight, wrist circumference, and the waist to hip ratio. Also, in regression analysis, age and sex
had an association with pulmonary function, but the weight did not show a significant relationship.
On the other hand, fat-free mass and visceral fat were significantly associated with pulmonary function.
One is direct and the other is inverse.
Conclusion: We observed a negative association between visceral fat and pulmonary function tests
and a direct association between Fat-free mass pulmonary function tests (FEV1 and FVC) adjusted
for age, sex, and anthropometric indices.