Does BMI Predict Variations in Pulmonary Function? Findings from A Cross-Sectional Study”

Background: Obesity, known to influence pulmonary function through mechanical and physiological mechanisms. However, the relationship between body mass index (BMI) and specific spirometric parameters remains inconsistent across populations. Objectives: Study aimed to evaluate the association between BMI and lung function by assessing correlations with spirometric indices and comparing pulmonary function across different BMI categories. Methods: A cross-sectional analysis was conducted on 99 adult participants who underwent spirometry. Lung function parameters – including forced vital capacity (FVC), Forced expiratory volume in 1 second (FEV1), FEV1/FVC ratio, slow vital capacity (SVC), maximal voluntary ventilation (MVV), and mid-expiratory flow (FEV25-75% )- were measured. Pearson’s correlation was used to assess associations between BMI and pulmonary indices, one way ANOVA was employed to compare variables across BMI groups. Results: BMI was positively and significantly correlated with FVC (r = 0.26, p<0.05), FVC% predicted (r = 0.21, p < 0.05), FEV1 (r = 0.35,p <0.01), and FEV1% predicted (r = 0.29, p < 0.05). No significant correlations were observed between BMI and MVV, SVC, SVC/FVC, or FEF 25-75%. With BMI categories, no statistically differences were observed in lung function indices (p>0.05), although overweight/obese individuals showed slightly higher mean FVC and FEV1 values. Conclusions: BMI demonstrated a modest positive correlation with selected lung function parameters (FVC, FEV1), suggesting that moderate increase in BMI do not adversely affect spirometric measures in younger adults. These findings highlight the need for further research considering age, fat distribution, and body composition when evaluating the impact of adiposity on respiratory function.