The relation between visceral fat and lung function in the general population is in part mediated by CRP and leptin.

Background: Abdominal obesity is associated with reduced lung function. It remains unclear whether this results from mechanical pressure or whether visceral fat also plays a role via inflammation. Our aim was to examine the association between visceral fat and lung function, and the role of inflammation.

Methods: In this cross-sectional analysis, visceral fat was measured by magnetic resonance imaging and lung function by spirometry. We examined the association between visceral fat and lung function, and mediation by CRP, GlycA, Fe_NO, leptin, and adiponectin.

Results: We included 2,266 participants, mean age 56 (6) years and 90 (56) cm² visceral fat. After adjusting for confounding factors including total body fat and waist circumference, per SD of visceral fat, FEV₁ was 3.6% lower (95% CI: -4.9,-2.4), and FVC was 3.6% (-4.6,-2.6) lower. No mediation was observed by GlycA, Fe_NO and adiponectin. CRP and leptin together mediated 22% of the association with FEV₁ and 19% with FVC.

Conclusion: In a middle-aged general population with a normal lung function, visceral fat was associated with reduced lung function. This association was for 20% mediated by CRP and leptin. Future research should explore the remaining mechanisms underlying the association between visceral fat and lung function.

Trial registration: CT.gov identifier NCT03410316.